DE102012218190A1 - Method for monitoring cooling/heating device of switchgear cabinet, involves triggering alarm for fault in cooling/heating device when time change of temperature of electronic circuit exceeds preset range - Google Patents

Abstract

The method involves switching of the electronic circuit of cooling/heating device from one active state to another active state, and recognizing the change of active state of electronic circuit. The temperature of the electronic circuit in another active state is detected and the checking of whether time change of temperature of electronic circuit exceeds the preset range. An alarm for fault in cooling/heating device is triggered when time change of temperature of electronic circuit exceeds the preset range. Independent claims are included for the following: (1) a control device for cooling/heating device; and (2) a switchgear cabinet.

Description

The invention relates to a method for monitoring a cooling or heating device, which is provided for controlling the temperature of a device with an electronic circuit, wherein the cooling or heating device comprises a fan which generates an air stream passing through the device and the electronic circuit. Furthermore, the invention relates to a monitoring device for a cooling or heating device, which is provided for controlling the temperature of a device with an electronic circuit, wherein the cooling or heating device comprises a fan, which is prepared for the generation of a device and the electronic circuit passing air flow , Finally, the invention relates to a cabinet, comprising a device to be tempered with an electronic circuit and
a blower, which is prepared for the production of the cabinet, the device and the electronic circuit passing air flow. Furthermore, the control cabinet comprises a monitoring device of the type mentioned.

Cooling or heating means for controlling the temperature of a device with a blower for generating an air flow are well known. For example, computers, devices in electrical cabinets and the like are often tempered in this way. Frequently, a filter is arranged on the supply side to remove dirt particles and the like from the air supplied to the device. But it is also known to arrange a filter on the exhaust side, for example, if the device secrets hazardous substances or dirt and the exhaust air must be cleaned to avoid environmental damage.

It is in the nature of the thing that with time dirt particles and the like deposit in the filter and thus increase the flow resistance of the same successively. This reduces the air flow and, consequently, the heat output supplied to or removed from the unit while the fan output remains the same. Therefore, the filter must be renewed if it is dirty, so as not to risk, for example, overheating and possibly destruction of the device to be tempered.

This can be done at regular intervals, regardless of a specific contamination of the filter, or at a certain level of contamination. From the prior art, some solutions are known to determine the degree of contamination of a filter, for example by the pressure loss is measured at the same. This requires a comparatively expensive differential pressure sensor, which is also technically limited use of very dirty cooling air.

Another way to determine the degree of contamination of a filter is in the WO 2002/19511 A1 disclosed. In this case, a cooling device comprises a fan and a filter arranged in the flow path. The fan is preferably driven at constant torque. Increases the speed of the fan now due to contamination of the filter, so an alarm signal can be triggered, which signals a dirty filter.

In addition to the mentioned contamination of the filter, other defects may occur in a cooling or heating device. For example, the blower for generating the air flow may be defective, for example due to engine damage, bearing damage or damage to an electronic control unit of the blower. In particular, if there is no filter on the supply side, dirt (for example, leaves and the like) can also settle in the ventilation system and clog it gradually. Plant growth in front of a suction opening can also disturb the ventilation system. Occasionally, animals in a ventilation system also seek supplements and may end up there. This too is one reason for a clogged ventilation system and consequently for cooling or heating with only more limited function.

It is an object of the invention to provide a further improved method for monitoring a cooling or heating device and a further improved monitoring device for this purpose. In addition, an improved control cabinet should be specified. In particular, the monitoring should be simplified and carried out with the aid of parameters which can be measured easily, or with the aid of parameters which under certain circumstances may already be determined or generated for other purposes and thus be able to fulfill a double benefit.

• a) Überführen der elektronischen Schaltung von einem ersten in einen zweiten Aktivitätszustand und/oder Erkennen einer solchen Änderung,
• b) Erfassen der Temperatur der elektronischen Schaltung im zweiten Aktivi tätszustand,
• c) Prüfen, ob eine zeitliche Änderung der Temperatur außerhalb eines vor gebbaren Sollbereichs liegt und
• d) Auslösen eines Alarms für eine Störung der Kühl- oder Heizeinrichtung, wenn das Ergebnis der Prüfung positiv ist.

The object of the invention is achieved by a method of the type mentioned above, comprising the steps:

• a) transfer of the electronic circuit from a first to a second state of activity and / or recognition of such a change,
• b) detecting the temperature of the electronic circuit in the second activity state,
• c) Checking whether a temporal change of the temperature is outside a specifiable target range and
• d) triggering an alarm for a failure of the cooling or heating device, if the result of the test is positive.

• – eine Schalteinrichtung zum Überführen der elektronischen Schaltung von einem ersten in einen zweiten Aktivitätszustand und/oder Mittel zur Erkennung einer solchen Änderung,
• – einen Temperatursensor zum Erfassen der Temperatur der elektroni schen Schaltung im zweiten Aktivitätszustand und
• – Mittel zum Prüfen, ob eine zeitliche Änderung der Temperatur außerhalb eines vorgebbaren Sollbereichs liegt und zum Auslösen eines Alarms für eine Stö rung der Kühl- oder Heizeinrichtung, wenn das Ergebnis der Prüfung positiv ist.

The invention is further achieved with a monitoring device of the type mentioned ge, comprising

• A switching device for transferring the electronic circuit from a first to a second activity state and / or means for detecting such a change,
• A temperature sensor for detecting the temperature of the electronic circuit in the second state of activity and
• - means for checking whether a temporal change of the temperature is outside a predetermined target range and for triggering an alarm for a fault tion of the cooling or heating device, if the result of the test is positive.

Finally, the object of the invention is achieved by a control cabinet of the type mentioned, comprising a monitoring device according to the invention.

According to the invention, therefore, a change in the temperature of the device to be cooled or heated, in particular an electronic circuit comprised thereof, for detecting a malfunction of the cooling or heating device (eg dirty filter, clogged ventilation system, defective blower due to bearing damage, engine damage, defect of the blower control, etc .) used. In this case, one makes use of the fact that a change in the state of activity of the electronic circuit and thus a change in the output of the electronic circuit power loss causes a change in temperature of the circuit when the cooling / heating power is not adjusted accordingly. Depending on the temperature difference between the electronic circuit and the temperature of the passing air, the temperature of the electronic circuit approaches the temperature of the passing air faster or less quickly. Another influencing parameter for this is also the power loss delivered by the electronic circuit during the temperature detection, which counteracts the mentioned temperature change.

If the temperature now changes more slowly than expected, this is an indication of a malfunction of the cooling or heating device, which leads to a reduction in the air flow and thus to a reduction in the cooling or heating power. The relevant target range can be determined by empirical experiments or with the help of computer models.

In particular, if a temperature sensor is already present on the electronic circuit for other purposes, a contamination detection can be realized in this way without significant additional effort. This is also very robust and reliable, since a contact of a sensor with the conveyed medium - unlike for example in a differential pressure gauge - can be avoided.

Advantageous embodiments and developments of the invention will become apparent from the dependent claims and from the description in conjunction with the figures.

It is favorable for the method according to the invention if, in addition, an ambient temperature is detected and the desired range depends on this. It is not always possible to assume a constant, known ambient temperature, as is the case, for example, in air-conditioned rooms or, to a lesser extent, in cellars. Therefore, if the ambient temperature is not known from the beginning and / or fluctuates comparatively strongly, it is favorable to detect this since the cooling or heating power depends on the temperature difference between the ambient temperature and the device to be tempered. Accordingly, different target ranges can be provided for different ambient temperatures or temperature differences. If the temperature difference between the electronic circuit and the ambient temperature is low, the temperature of the electronic circuit changes less rapidly than the temperature of the passing air, so that a slight change in the temperature over time does not necessarily indicate that the cooling or heating device is malfunctioning. By appropriate adjustment of the target ranges this fact is taken into account. The ambient temperature can be measured, for example, via a temperature sensor provided for this purpose, or can also be determined via centrally provided weather data, for example via a wired communication connection or a radio connection. For example, related services can be used on the Internet. If not so high demands are placed on the detection reliability of the disturbance of the cooling or heating device, a measurement of the ambient temperature can still be omitted even if it is unknown and / or varies relatively strongly. The detection safety of the disturbance of the cooling or heating device increases with decreasing fluctuation of the ambient temperature and decreases with increasing fluctuation.

It is advantageous if the steps b) to d) are carried out when the ambient temperature and / or the difference between the ambient temperature and the temperature of the electronic circuit and / or a power supplied to the electronic circuit at the beginning of the second state of activity in a predetermined range lie. In this variant of the invention, it is ensured that the expected temperature change is large enough or takes place quickly enough so that measurement tolerances do not unintentionally lead to a false alarm when the temperature is too flat.

It is favorable for the method according to the invention if in addition a humidity and / or an air density of the air flow are detected and the desired range depends on this or these. Since the air humidity and the air density also have an influence on the cooling performance (moist or dense air cools more strongly), the air humidity and / or the air density can also be determined. The statements made for the ambient temperature apply mutatis mutandis. For example, the air humidity and / or the air density can be determined by separate sensors or centrally provided weather data. The steps b) to d) are advantageously carried out only if the air humidity and / or air density of the air flow is within a predeterminable range and thus a sufficiently strong temperature change of the electronic circuit is to be expected.

It is also advantageous if an electrical power which is conducted via the said electronic circuit is detected and the steps b) to d) are carried out if a temporal change of the power over a predefinable threshold value is detected. Again, this is one way to determine whether the expected temperature change will be strong enough to provide a meaningful result before testing the refrigerator or heater. For this purpose, the temporal gradient of the power can be evaluated or else the power can be determined at two points in time and the power difference compared with a threshold value. It is also possible to compare the time required for a certain power change with a threshold value. As a particularly advantageous for the inventive method, a sudden change in the electrical power has been found.

Of course, the parameters temperature difference, power, humidity and air density or parts thereof may also be combined to determine whether steps b) to d) should now be carried out or not.

It is also advantageous if the stated power is determined via the power supplied to an energy converter for generating electrical current, which is conducted via the electronic circuit. Optionally, to determine whether steps b) to d) are to be carried out, instead of the power supplied via the inverter, it is thus also possible to use, e.g. used in a photovoltaic system radiated power.

It is particularly advantageous if step a) is carried out by activating or deactivating the electronic circuit. As already mentioned, it is advantageous if the power conducted via the electronic circuit breaks down as sharply as possible or increases as much as possible (in particular erratic) and the other circumstances mentioned (eg suitable ambient temperature, air humidity, air density) fit to an accurate statement about be able to meet the state of the cooling or heating device. Sometimes, however, such a power dip or increase does not occur or does not occur at the desired time. For this reason, it is provided in this variant of the invention to cause such a power dip or increase in power in step a) by activating or deactivating the electronic circuit. The temperature of the device then strives as already explained to a different temperature level. The strength of this temperature change is evaluated as usual in order to be able to make a statement about the disturbance of the cooling or heating device.

• – die elektronische Schaltung zumindest einen Kühlkörper zur Temperie rung wenigstens eines Teils der genannten Schaltung umfasst,
• – das Gebläse einen den Kühlkörper passierenden Luftstrom erzeugt und
• – dass anstatt der elektronischen Schaltung nur der genannte Schaltungs teil für das erfindungsgemäße Verfahren herangezogen wird.

It is also favorable if

• - The electronic circuit comprises at least one heat sink for tempering tion of at least a portion of said circuit,
• - The blower generates an airflow passing through the heat sink and
• - That instead of the electronic circuit only the said circuit part is used for the inventive method.

In this case, the blower generates a stream of air passing through the heat sink, and instead of the electronic circuit only the said circuit part is used for the method according to the invention. This means that only the activity state of this circuit part has to be changed and its temperature or that of the associated heat sink must be determined. In this way, a particularly good coupling between the air flow and the circuit is given, so that a compensation of the temperature of the circuit part when changing the state of activity corresponding to rapidly. It is particularly advantageous in this context if the temperature sensor is arranged on the at least one heat sink, since said coupling and the associated rapid temperature compensation are even more pronounced. Moreover, a temperature sensor is often already provided on the heat sink in order to detect an overload of the device and to be able to switch off this if necessary. This temperature sensor can thus fulfill a double benefit.

It is particularly advantageous if step a) is carried out by activating an electrical heating element arranged in the circuit, in particular on the heat sink. Another way to determine the state of the cooling or heating device with the method according to the invention consists in that step a) is performed by activating an in the circuit, in particular on the heat sink, arranged electrical heating element. This can in principle be done at any time, but a particularly high change in the temperature of the heat sink is expected then when the device is not in operation. If the heating element is now activated, the electronic circuit, in particular the heat sink, on which the heating element is arranged, is heated or cooled down when the heating element is switched off. As already described, this temperature change can be used to determine the state of the cooling or heating device.

It is particularly advantageous if a plurality of setpoint ranges can be predetermined, each setpoint range indicating an assigned degree of disturbance of the cooling or heating device, in particular an associated degree of soiling of the filter, and wherein the alarm triggered when a specific setpoint range is exceeded contains information about the assigned degree of contamination , This variant enables the delivery of differentiated alarm messages. For example, levels of pollution and associated alarms for light, medium and heavy pollution can be defined. It is conceivable to activate colored lamps or light-emitting diodes according to a traffic light system. For example, "green" means limited cooling or heating power (especially incipient pollution) but still in order, "yellow" marginal cooling or heating power or pollution, and "red" lack of cooling or heating power or excessive pollution.

It is favorable if the alarm is transmitted via a mobile radio network and / or the Internet. In this way, the alarm of the person responsible for the care of the cooling or heating device can be delivered directly, for example by means of the Short Message Service (SMS) or by email. The person concerned does not need to be present to be able to take notice of an alert.

It is also beneficial if an alarm is recorded in a memory. This makes it easier for the manufacturer of the device to be tempered to have any discussion about the question of guilt, for example if it should become defective because of a clogged filter. If it is determined that requests to replace the filter have been ignored by the operator of the said device, this is a strong indication that the fault lies with the operator of the broken device.

In order to increase the reliability of the method according to the invention, it can be provided that in step d) a further test of the cooling or heating device is performed and only then alarm for a malfunction of the cooling or heating device is triggered when the result of both tests is positive , It can be provided that the further test is carried out in the same manner as the first test. But it is particularly advantageous if the further test is carried out in a different manner, as will be explained below. Of course, more than two tests can form the basis for deciding whether an alarm should be triggered or not.

• – Erfassen eines die Leistung des Gebläses kennzeichnenden Parameters und
• – Prüfen, ob der Parameter außerhalb eines vorgebbaren Sollbereichs liegt, umfasst.

It is advantageous in this context if a power of the fan is increased with increasing deviation between the target and actual temperature of the device and the further examination of the cooling or heating device, the steps:

• - Detecting a characteristic of the performance of the blower and parameters
• - Check whether the parameter is outside a predefined target range includes.

Frequently, a cooling / heating device comprises a control which increases a power of the fan with increasing deviation between the setpoint and actual temperature of the device to be tempered. In this variant of the invention, the power supplied to the fan or the power supplied by it is used directly or indirectly to detect a malfunction of the cooling or heating device. In this case, one makes use of the fact that the said control the performance of the fan with increasing degree of contamination of the ventilation system, in particular the filter, nachzuführen to compensate for the increased pressure loss and to the air flow and thus the cooling or heating power constant hold. A parameter which characterizes the performance of the fan can be determined very simply or is already known to the regulation for controlling the temperature of the device. In this way, additional pollution detection can thus be realized without significant additional effort, which is also very robust and reliable, since contact of a sensor with the conveyed medium - unlike, for example, a differential pressure gauge - can be avoided. It is advantageous if the blower parameter is also used to define the desired range or ranges in step c) and to decide whether steps b) to d) are to be performed.

It is also advantageous, if as the performance of the blower characterizing parameters applied to a drive motor of the fan electrical voltage (eg measured with a voltmeter), the electrical current received by a drive motor (eg measured with an ammeter), the recorded by a drive motor electrical power (eg measured with a wattmeter), the actual speed of a Drive motor (eg measured with a tachometer) and / or the target speed of a drive motor is provided. These parameters can be very easily detected or have ever been detected for other purposes. For example, a target speed, which is specified by the control / regulation for controlling the temperature of the device, be taken directly for the inventive method. Likewise, it is conceivable that the control / regulation specifies a desired voltage, a desired current or a desired power, which can be adopted accordingly.

It is also advantageous in this context if, in addition, a temperature of the device, in particular a difference between a setpoint and an actual temperature, is detected and the setpoint range for the blower parameter depends on this. The power supplied to the blower also depends on the temperature of the appliance itself or the temperature difference due to the temperature control of the appliance, because as the deviation between the actual temperature and the set temperature increases, the performance of the blower is also increased. An increased fan power thus does not necessarily result from a malfunction of the cooling or heating device, but may, for example, be due to an increased power requirement on the device to be cooled. Therefore, there is a fundamental risk that the temperature-induced power increase is "misinterpreted" as a failure of the cooling or heating device. The detection uncertainty also decreases with decreasing variation of the device temperature. This means that with constant power of the device also a constant heat output has to be removed. An increase in the fan power is therefore very likely due to a malfunction of the cooling or heating device.

However, if the power of the device fluctuates so much that the fluctuations can no longer be neglected (for example, this is often the case with inverters), the said power is taken into account in an advantageous variant of the invention. For example, the power currently supplied to the device or the power dissipation of the device (which basically leads to heating of the device) is detected and the target range for checking whether the parameter characterizing the performance of the blower is outside a predefined target range is adjusted accordingly. At higher device power, the target range is slightly widened, so that an increased blower output, which is due to the increased performance of the device to be tempered, does not lead to an alarm being triggered. Accordingly, the target range is somewhat narrowed with smaller device performance. Alternatively, the test can also be triggered at a given power of the device or carried out at constant power of the device. It is particularly advantageous if the test of the cooling or heating device is always carried out at the same power of the device, since the individual measurement results, i. E. the size of a parameter characterizing the performance of the blower can be compared particularly well with each other.

It is also advantageous if, in addition, an ambient temperature is detected and the desired range for the blower parameter depends on this. In particular, if the ambient temperature fluctuates greatly, the already mentioned detection uncertainty can be reduced by measuring the ambient temperature.

• – Erfassen der Differenz zwischen der Umgebungstemperatur und der Temperatur der elektronischen Schaltung und
• – Prüfen, ob die Differenz außerhalb eines vorgebbaren Sollbereichs liegt, umfasst.

It is also advantageous if the power loss of the device and a performance-descriptive parameters of the blower, for example, the speed is kept constant and the further examination of the cooling or heating device, the steps:

• - Detecting the difference between the ambient temperature and the temperature of the electronic circuit and
• - Check whether the difference is outside a predetermined target range includes.

In this variant, the air flow provided for the temperature control is less in the case of a malfunction of the cooling or heating device and thus the cooling / heating power than if the cooling or heating device is not disturbed. This manifests itself in the fact that the difference between the ambient temperature and the temperature of the electronic circuit increases. If it exceeds a certain threshold, this is therefore an indication of a malfunction of the cooling or heating device.

It is also advantageous if an inverter is provided in the control cabinet according to the invention as an apparatus to be tempered. Inverters can be found quite frequently in control cabinets, for example in solar systems, welding systems, motor control systems and the like. Frequently, relatively high powers are conducted via such an inverter, which is why it must be cooled as a rule. The advantage of the invention is therefore particularly apparent at this point.

It is advantageous if the circuit part to be tempered is formed by at least one switching transistor or at least one switching thyristor of the inverter. The components mentioned carry the majority of the electrical power of the inverter and therefore also emit a correspondingly high power loss, in particular to a heat sink connected to the switching transistors or switching thyristors

It should be noted at this point that the variants mentioned for the method according to the invention and the resulting advantages relate equally to the monitoring device according to the invention and the control cabinet according to the invention. The same is true, of course, vice versa.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Each shows in a highly schematically simplified representation:

1 the schematic structure of an inverter or a solar system;

2 a first exemplary variant of a cabinet according to the invention;

3 an example of the course of an inverter powered by a photovoltaic system power and its temperature;

4 an exemplary table in which an association between the temperature of an inverter and a plurality of target ranges for the rotational speed of a blower is included and

5 a second exemplary variant of a cabinet according to the invention.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions.

All information on ranges of values in objective description should be understood to include any and all sub-ranges thereof, eg, the information 1 to 10 should be understood to mean that all sub-ranges, starting from the lower limit 1 and the upper limit 10 are included, ie all sub-areas start with a lower limit of 1 or greater and end at an upper limit of 10 or less, eg 1 to 1.7, or 3.2 to 8.1 or 5.5 until 10.

In 1 shows a structure of a conventional inverter 1 , As the individual components or assemblies and functions of inverters 1 are already known from the prior art, will not be discussed in detail below.

The inverter 1 has at least one input DC-DC converter 2 , a DC link 3 and an output DC-AC converter 4 on. At the input DC-DC converter 2 is an energy source 5 or a power generator connected, which preferably from one or more parallel and / or series-connected solar modules 6 be formed. The inverter 1 and the solar modules 6 are also referred to as "photovoltaic system" or as "PV system". The output of the inverter 1 or the output DC-AC converter 4 can with a supply network 7 , eg a public or private alternating voltage network or a multi-phase network, and / or with at least one electrical consumer 8th , which represents a load, be connected. For example, becoming a consumer 8th by an engine, a refrigerator, a radio, etc. formed. Likewise, the consumer can 8th also represent a home care. The individual components of the inverter 1 like the input DC-DC converter 2 etc., can via a data bus 9 with a control device 10 be connected.

Preferably, such an inverter is used 1 as a so-called grid-connected inverter 1 , whose energy management is then optimized, as much energy in the supply network 7 feed. As is known in the art, consumers are 8th over the supply network 7 provided. Of course, several inverters connected in parallel can also be used 1 be used. This allows more energy to operate the consumer 8th to be provided.

This energy comes from the energy source 5 supplied in the form of a DC voltage, which via two connecting cables 11 . 12 with the inverter 1 connected is. The control device 10 or the controller of the inverter 1 is formed for example by a microprocessor, microcontroller or computer. About the control device 10 can be a corresponding control of the individual components of the inverter 1 like the input DC-DC converter 2 or the output DC-AC converter 4 , in particular the switching elements arranged therein, are made. In the control device 10 For this purpose, the individual control processes are controlled by appropriate software Programs and / or data or characteristics stored.

Furthermore, with the control device 10 controls 13 connected by which the user, for example, the inverter 1 configure and / or display operating states or parameters - for example by means of LEDs - and can set. The controls are for example via the data bus 9 or directly with the control device 10 connected. Such controls 13 are for example on a front of the inverter 1 arranged so that an operation from the outside is possible. Likewise, the controls 13 also directly to modules and / or modules within the inverter 1 be arranged.

2 now shows like the inverter 1 , which comprises an electronic circuit, in a housing or a control cabinet 14 can be arranged. The control cabinet 14 has a supply air opening 15 and an exhaust port 16 on. At the supply air opening 15 is a filter 17 and at the exhaust port 16 a fan 18 arranged. Will the blower 18 activated, ambient air flows through the supply air opening 15 , the filter 17 , on the inverter 1 over, through the blower 18 and finally through the exhaust air opening 16 , The flow of air is in the 2 indicated by arrows. In the present case it is assumed that the ambient air is cooler than the inverter 1 why it is cooled, and more so, the more power the drive motor of the fan 18 is supplied. For this purpose, an optional control system 19 provided, which is the temperature of the inverter 1 measures and the blower 18 accordingly controls, ie its power increases when the temperature of the inverter 1 or the difference between its setpoint and actual temperature increases. For the sake of simplicity, however, it is assumed for the time being that the regulation / control 19 is not provided or integrated in a higher-level control, not shown.

Furthermore, the arrangement comprises a monitoring device 20 the cooling or heating device, which with a temperature sensor 21 for detecting the temperature of the electronic circuit and a temperature sensor 22 for detecting the temperature of the intake air, ie the ambient temperature comprises. Furthermore, the monitoring device comprises 20 a switching device, not shown, for transferring the electronic circuit from a first to a second activity state and / or means for detecting such a change, and means for checking whether a change in temperature over time is outside a predetermined target range and for triggering an alarm for a fault the cooling or heating device, in particular for a clogged filter 17 if the result of the exam is positive.

The function of in 2 The arrangement shown will now be based on the PV system 1 with further reference to 3 explained.

3 shows the typical course of the sun-injected power P over time t over the course of a day (solid line). The power P increases gradually in the morning, reaching the maximum at around noon and falling towards evening. 3 shows only the basic course, of course, this also depends on the orientation of the PV system and objects that shade them during the day from. In addition, the time course of the temperature T of the inverter is also 1 registered (dash-dotted line). This rises in the morning, then remains because of the cooling effect of the blower 18 at constant power P is approximately constant and drops off in the evening.

By way of example, it is now assumed that in the morning a dense cloud field passes over the PV system and obscures the otherwise cloudless sky. This manifests itself in a relatively strong and sudden incidence of the radiated power P. But this changes just as suddenly over the inverter 1 Guided power P, which is essentially due to the radiated power P times the efficiency of the solar modules 6 is determined. According to the invention, such a transfer of the electronic circuit from a first to a second state of activity, in this case the onset of the power P, in a step a) of the monitoring device 20 recognized.

During shading, the temperature approaches T because of the inverter 1 stroking air in a conventional manner the ambient temperature, in accordance with the known function .DELTA.T · 1 - e ^{t / τ} . In the concrete example is also still in spite of the clouds over the inverter 1 Guided (residual) power P to take into account, so the target limit is slightly above the ambient temperature.

According to the invention, in a step b) the temperature T of the electronic circuit is detected in the second activity state, in a step c) checked whether a temporal change in temperature T is outside a predetermined target range and in a step d) an alarm for a malfunction of the cooling - or heating device triggered when the result of the test is positive. If the temperature T does not decrease rapidly enough, this is a strong indication that the cooling or heating device is disturbed, for example because of the filter 17 is clogged, since the Volume flow and thus the cooling effect despite the fan running 18 is low. For this purpose, for example, it can be checked whether the temporal gradient of the temperature T lies in an expected range, or, for example, the temperature T is determined at two times and the temperature difference is compared with a threshold value.

It is also possible to compare the time required for a certain temperature change with a threshold value.

Analog can also be the subsequent heating of the inverter 1 be used for the detection of a malfunction of the cooling or heating device when the cloud field is passed, and then the full power P is radiated back into the PV system.

For the temperature change to be meaningful, i. strong enough fails, it can also be provided that the steps b) to d) are carried out when the ambient temperature and / or the difference between the ambient temperature and the temperature T of the electronic circuit at the beginning of the second state of activity within a predetermined range, in particular above a threshold. Thus, a disturbance of the cooling or heating device with initially high irradiation power P and low outside temperature, ie. for example, in the morning or in winter.

In this context, it is also advantageous if an electric power P, which is guided via said electronic circuit, is detected and the steps b) to d) are carried out, if a temporal change of the power P is detected beyond a predefinable threshold , For this purpose, the temporal gradient of the power P can be evaluated or else the power P can be determined at two times and the power difference compared with a threshold value. It is also possible to compare the time required for a certain power change with a threshold value.

Since the air humidity and the air density also have an influence on the cooling performance (moist or dense air cools more strongly), the air humidity and / or the air density can also be determined, for example by separate sensors or centrally provided weather data, which are transmitted via a wired communication connection or a radio connection are received. Accordingly, the steps b) to d) are carried out when the air humidity of the air flow and / or air density is within a predeterminable range and thus a sufficiently strong change in temperature of the electronic circuit is to be expected.

Of course, the above parameters, i. Temperature difference, power, humidity and air density or parts thereof are also combined to determine whether the steps b) to d) should now be carried out or not.

In a very similar way, the parameters can be used individually or in any combination to determine the setpoint range for the temperature change, which is relevant for triggering an alarm. For example, with little change in power P (which is just a small difference between the temperature T at the beginning of the second state of activity of the inverter 1 and the final temperature, which is the temperature T of the inverter 1 asymptotically approximate, even a slight change in temperature indicates a malfunction of the cooling or heating device and vice versa.

In the present case, it was assumed that the control cabinet 14 is set up in the outdoor area, which is why a measurement of the ambient temperature or a collection on centrally provided weather data makes sense. Frequently, however, control cabinets are also installed in rooms with a constant or approximately constant temperature T, for example in air-conditioned rooms or cellars. A detection of the ambient temperature can then be omitted.

Optionally, to determine whether steps b) to d) are to be performed instead of via the inverter 1 guided power P and the radiated power P in the PV system are used. For example, in the field of solar modules 6 a photosensitive sensor mounted and with the monitoring device 20 connected. In general, the invention can of course also be used away from PV systems. In particular, it is advantageous in inverters of energy converters for generating electrical power, thus, for example, in wind power plants, tidal power plants and the like.

As already mentioned, it is also advantageous if the power P guided via the electronic circuit or its power dissipation (which basically leads to heating of the electronic circuit) collapses as much as possible and the other circumstances mentioned are also suitable (eg ambient temperature, air humidity, air density) ) to give an accurate statement about the state of the cooling or heating device, in particular the filter 17 to be able to meet. Sometimes, however, these circumstances do not occur or do not occur at the desired time. Passing clouds can not be "ordered". For this reason, it can be provided in a variant of the invention that step a) by activating or deactivating the electronic circuit is performed. In 3 This condition is shown shortly after noon. The inverter is deactivated so that no more power P is passed through it. The temperature T of the inverter thus strives for by the blower 18 caused airflow to the ambient temperature too. An examination of the cooling or heating device can therefore be carried out in the manner already described.

As a rule, the power section of an inverter 1 cooled by a heat sink. With this will be at least part of the electronic circuit, in the case of an inverter 1 usually its switching transistors or switching thyristors, substantially cooled. It is advantageous in this case, if the temperature sensor 21 is arranged on the at least one heat sink. In this case, the blower generates 18 a passing the heat sink air flow, and instead of the electronic circuit only the said circuit part is used for the inventive method. This means that only the activity state of this circuit part has to be changed and its temperature T or that of the associated heat sink must be determined.

Another way to determine the state of the cooling or heating device with the method according to the invention is that step a) by activating a in the circuit, in particular on a heat sink, arranged electrical heating element is performed. This can in principle be done at any time, a particularly high change in the temperature T of the heat sink but then expected when the inverter 1 not in operation. In the case of a PV system, this is to be expected during the night 3 The heating element is therefore activated at night, whereby the electronic circuit, in particular the heat sink, on which the heating element is arranged, is heated in the manner already mentioned or cools again when the heating element is switched off. As already described, this temperature curve can be used to determine the state of the cooling or heating device.

If the blower 18 is not operated continuously, it can be advantageously activated only after the heating of the heat sink with the described heating element, so that the heat sink is then actively cooled.

If the circuit is an inverter 1 comprises or is formed by this, then step a) by transferring the inverter 1 be carried out in an operation with a defined power loss. In this variant, the aforementioned method can also be carried out without a separate heating element. Such a defined power loss can be generated by operating the inverter in reactive power mode: The inverter does not feed any active power of the PV system, but only reactive power into the grid. He works as a reactive power compensation system in the so-called "phase shifter operation". The resulting losses in the inverter heat the electronic circuit with the associated heat sink. After the end of the supply of reactive power, the circuit cools down again. For this purpose, no sunlight is needed; This process can, for. B. take place at night By the phase shifter operation, the mains voltage is changed at the feed point. It is therefore important to allow phase shifter operation only in a range in which the mains voltage is not unduly changed, ie, that monitored during idle power operation of the inverter, in particular by the control device of the inverter, the fed reactive power and the mains voltage and is regulated in that the change in the mains voltage of the public supply network is within a permissible range defined in the inverter. For this purpose, it is possible for corresponding setpoints or range for the permissible change in the mains voltage to be stored in the inverter so that an increase or decrease in the reactive power fed in is changed within the specified limits at the supply voltage detected at the feed-in point.

Furthermore, it is possible that the temperature inside the inverter is detected at the same time so that the inverter can not overheat. After the inverter has been heated to a predefined temperature, the cooling or heating device, in particular the fan, is activated and the time is taken until the inverter has been cooled to a defined low temperature, ie the running time for cooling from a first value ( heated) is cooled to a defined second value (lower value), so that conclusions are drawn on the basis of the determined time on the degree of contamination. For this purpose, a corresponding table can be deposited, the appropriate parameters of the heating and cooling device, such as the speed of the fan, the nominal temperature, etc. are stored for the corresponding maturities.

In the following, it will now be discussed in more detail in what form an alert can be made. For example, this can be done in a conventional manner by optical and / or acoustic signals. In particular, since energy generating systems are often installed in remote locations, it is particularly advantageous if the alarm is transmitted via a mobile network and / or the Internet, for example as a text or voice message.

In addition, it can be provided that a plurality of desired ranges can be predetermined, each desired range having an associated degree of disturbance of the cooling or heating device, in particular an associated degree of soiling of the filter 17 , and wherein the alarm which is triggered when a specific setpoint range is exceeded contains information about the assigned degree of soiling. The in 3 The course of temperature shown runs so much flatter, the more impaired the cooling or heating device or the more polluted the filter 17 is because its flow resistance increases with the degree of contamination. This circumstance can be made use of and trigger a differentiated alarm. For example, different alerting levels may be provided (here referred to the state of the filter), such as "filter slightly contaminated - reorder filter", "filter borderline polluted - filter ready" and "filter heavily contaminated - filter exchange".

In addition, it can also be provided that an alarm is logged. This facilitates the manufacturer of the cabinet 14 any discussion about the question of guilt, if eg the inverter 1 should become defective due to overheating. Is found that prompts to swap the filter 17 ignored by the operator of the PV system, this is a strong indication that the fault for the broken inverter 1 the operator is the same.

In order to increase the reliability of the method according to the invention, it may further be provided that in step d) a further test of the cooling or heating device is performed and only then alarm for a malfunction of the cooling or heating device is triggered, if the result of both tests positive is. It can be provided that the further test is carried out in the same manner as the first test. It is particularly advantageous, however, if the further test is carried out in a different way. Of course, more than two tests can form the basis for deciding whether an alarm should be triggered or not.

For example, it can be provided that a power of the blower 18 with increasing deviation between setpoint and actual temperature of the inverter 1 is increased. In the 2 this is through the regulation / control 19 indicated which the temperature T of the inverter 1 over the already mentioned temperature sensor 21 determined. Of course, but also a separate temperature sensor can be used, which is particularly advantageous if the monitoring device 20 and the regulation / control 19 supplied by different manufacturers.

• – Erfassen eines die Leistung des Gebläses 18 kennzeichnenden Parame ters und
• – Prüfen, ob der Parameter außerhalb eines vorgebbaren Sollbereichs liegt.

Further testing of the cooling or heating device now comprises the steps:

• - Detecting a the performance of the blower 18 characterizing parameters and
• - Check whether the parameter is outside a predefined target range.

• – die an den Antriebsmotor des Gebläses 18 angelegte elektrische Span nung mit Hilfe einer Spannungsmesseinrichtung (Voltmeter) und/oder
• – den vom Antriebsmotor aufgenommene elektrischen Strom mit Hilfe ei ner Strommesseinrichtung (Amperemeter) und/oder
• – die vom Antriebsmotor aufgenommene elektrische Leistung, mit Hilfe einer Leistungsmesseinrichtung (Wattmeter) und/oder
• – die Ist-Drehzahl des Antriebsmotors mit Hilfe einer Drehzahlmesseinrich tung (z.B. optischer oder induktiver Drehzahlmesser) ermittelt und/oder
• – die Soll-Drehzahl des Antriebsmotors von der Regelung/Steuerung 19 übernimmt.

For this purpose, a monitoring device 20 be provided, wel che:

• - to the drive motor of the blower 18 applied electrical voltage voltage using a voltage measuring device (voltmeter) and / or
• - The electrical current absorbed by the drive motor by means of egg ner current measuring device (ammeter) and / or
• - The electrical power absorbed by the drive motor, using a power meter (Wattmeter) and / or
• - The actual speed of the drive motor using a Drehzahlmesseinrich device (eg, optical or inductive tachometer) determined and / or
• - The target speed of the drive motor of the controller / control 19 takes over.

If one parameter or several parameters exceed a predefinable target range, then it can be assumed that there is a malfunction of the cooling or heating device, in particular if the temperature T of the inverter 1 and have not or only slightly changed the ambient temperature. However, this is quite often the case, for example when the control cabinet 14 located in an air-conditioned room or a room with more or less constant temperature (eg basement) and the inverter 1 supplied power P also varies only slightly. Of course, the monitoring device according to the invention works 20 even under unfavorable conditions, ie strongly fluctuating temperature T of the inverter 1 or strongly fluctuating ambient temperature, if greater uncertainties regarding an alarm can be accepted.

Advantageously, said power P can however also be taken into account, for example by detecting the instantaneous power of the device and corresponding adaptation of said setpoint range. At higher power P, the setpoint range is slightly widened, so that an increased blower output, which is due to the increase in power P, does not yet trigger an alarm. Accordingly, the target range is somewhat narrowed at lower power P. Alternatively, the test can also be triggered at a predetermined (constant) power P.

The reliability of the method according to the invention can be further increased if, in addition to the performance parameter of the blower 18 the temperature T of the inverter 1 or the difference between its setpoint and actual temperature and / or the ambient temperature or the difference between the ambient temperature and the setpoint or actual temperature of the inverter 1 is detected and the target range of this / this depends. Not only a greater impairment of the cooling or heating, such as a more polluted filter 17 , an increase in the blower 18 supplied power, but also a higher temperature T of the inverter 1 and / or a higher ambient temperature or greater values of said temperature differences, these additional parameters are used to specify the desired range more accurately. For example, a certain speed of the fan 18 at a relatively low temperature T of the inverter 1 already lead to an alarm, whereas the same speed at a higher temperature T of the inverter 1 still leads to no alarm. The monitoring device 20 is with a temperature sensor 21 connected, which measures the temperature of the supplied air.

In addition, it can also be provided for the additional test that a plurality of desired ranges can be predetermined, each desired range having an associated degree of disturbance of the cooling or heating device, in particular an associated degree of soiling of the filter 17 , and wherein the alarm which is triggered when a specific setpoint range is exceeded contains information about the assigned degree of soiling. The blower 18 supplied power is of course the same, the higher the cooling or heating device affected or the more polluted the filter with constant cooling capacity 17 is, since its flow resistance so increases with the degree of contamination. As already mentioned, a differentiated alarm can be triggered in this way. For example, different ones may be on a filter 17 related alerting levels may be provided, such as "filter slightly contaminated - reorder filter", "filter borderline polluted - filter ready" and "filter heavily contaminated - filter replace".

The target ranges can be stored, for example, in the form of a table. 4 shows an example of this, in which a temperature T _{W of} the inverter 1 maximum speeds n _LV for a slight malfunction of the cooling or heating device (a slightly soiled filter 17 ), maximum speeds n _MV for a medium failure of the cooling or heating device (a medium soiled filter 17 ) and maximum speeds n _SV for a severe malfunction of the cooling or heating device (a heavily soiled filter 17 ) be assigned. Is the temperature T _{W of} the inverter 1 For example, 25 ° C and it is a speed of more than 1200 U / min on the blower 18 measured, so is an alarm for a mean disturbance of the cooling or heating device or an average pollution of the filter 17 triggered. The illustrated table is intended to give an example of a way of realizing the invention. Of course, customary modifications of the table are conceivable. In particular, instead of the temperature T _{W of} the inverter 1 the ambient temperature can be used to determine a desired range. Be the temperature T _{W of} the inverter 1 and taking into account the ambient temperature, then a multi-dimensional table may also be provided. Intermediate values can be interpolated in a known manner. Alternatively or in addition to the temperature T _{W of} the inverter 1 can also be considered its power or power loss in another dimension of the table

As an alternative to the table or in addition, it is also conceivable that the assignment of the temperature T _{W of} the inverter 1 and / or the ambient temperature to the maximum rotational speeds n _LV , n _MV , n _SV for a malfunction of the cooling or heating device or a dirty filter 17 using a function, such as a polynomial function.

• – Erfassen der Differenz zwischen der Umgebungstemperatur und der Temperatur der elektronischen Schaltung und
• – Prüfen, ob die Differenz außerhalb eines vorgebbaren Sollbereichs liegt.

In another variant of the invention is by the control / regulation 20 a speed of the blower 18 kept constant. Further testing of the cooling or heating device then comprises the steps:

• - Detecting the difference between the ambient temperature and the temperature of the electronic circuit and
• - Check whether the difference lies outside a predefined target range.

In this variant, the air flow provided for the temperature control decreases in the event of a malfunction of the cooling or heating device and thus the cooling / heating power. This manifests itself in the fact that the difference between the ambient temperature and the temperature of the electronic circuit is greater. If it exceeds a certain threshold, this is therefore an indication of a malfunction of the cooling or heating device. In this variant of the invention, the power P supplied to the circuit can also be taken into account, for example by detecting the instantaneous power P of the circuit and corresponding adaptation of the specified range. For a higher power P, the desired range is again widened somewhat, so that an increased blower power, which is due to the Increasing the power P is justified, yet does not lead to the triggering of an alarm. Accordingly, the target range is somewhat narrowed at lower power P. Alternatively, the test can also be triggered at a predetermined (constant) power P.

5 now shows a somewhat modified arrangement in a cabinet 14 ' , Here is the fan 18 supply side directly behind the filter 17 arranged. In addition, the cooling air in a separate cooling air duct 23 through the control cabinet 14 ' guided. Unlike the in 2 illustrated cabinet 14 are the regulation / control 19 as well as the monitoring device 20 in the inverter 1 integrated. Finally, the temperature sensor 21 outside on the control cabinet 1 and not arranged in the flow of the cooling air.

Of course, the characteristics of the 2 and 5 also be exchanged arbitrarily. For example, the regulation / control 19 and / or the monitoring device 20 also directly in the inverter 1 to 2 be arranged.

It would also be conceivable that the blower 18 in the flow of the cooling air in front of the filter 17 is arranged. It would also be conceivable that the filter 17 is arranged on the exhaust side. This is particularly advantageous if the exhaust air is still used for other purposes, such as the temperature of another device, and should be cleaned. It is also conceivable, of course, that several filters 17 and / or blower 18 in the control cabinet 14 are arranged. In particular, the flow profile of the cooling air can also be branched.

In addition, it is also conceivable that the facilities presented are not for cooling the inverter 1 , but used for heating a device, if this is cooler than the supplied air. For example, an accumulator could be heated to operating temperature.

The monitoring device 20 may be in software and or hardware. For example, it may be provided for a microcontroller. Preferably, the monitoring device 20 also be part of a software of the device to be tempered.

Finally, it is stated that the invention - although it has been explained with reference to an inverter for a solar system and there is advantageous - of course, in other cooling / heating devices can be used. In particular, a device according to the invention can also be used in a welding inverter.

In addition, the invention is not limited to the use of air as a cooling medium, but can be used in connection with any media, in particular with any gases and liquid media. Instead of cooling air is thus generally a cooling / heating medium with the aid of a fluid energy machine to be tempered device 1 past. For example, cooling water can be passed by means of a cooling water pump on the device to be tempered.

The embodiments show possible embodiments of a cabinet according to the invention 14 . 14 ' , It should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather also various combinations of the individual embodiments are possible with each other and this possibility of variation due to the teaching of technical action by objective invention in the ability of this on this technical Area professional. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiment variant, includes the scope of protection.

As a matter of precaution, it should be pointed out that for a better understanding of the design of the control cabinet 14 . 14 ' this or its components have been shown partially uneven and / or enlarged and / or reduced. Basically it is pointed out that the device 1 can be designed as an inverter.

The task underlying the independent inventive solutions can be taken from the description.

LIST OF REFERENCE NUMBERS

1

 inverter

2

 Input DC-DC converter

3

 DC

4

 Output DC-AC converter

5

 energy

6

 solar Panels

7

 network

8th

 consumer

9

 bus

10

 control device

11

 connecting cable

12

 connecting cable

13

 operating element

14

 switch cabinet

15

 Supply air opening

16

 Exhaust opening

17

 filter

18

 fan

19

 Regulation / control

20

 monitoring device

21

 Temperature sensor electronic circuit

22

 Temperature sensor supply air

23

 Cooling air duct

P

 power

T

 temperature

t

 Time

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2002/19511 A1 [0005]

Claims (25)

Method for monitoring a cooling or heating device, which is used for tempering a device ( 1 ) is provided with an electronic circuit, wherein the cooling or heating device is a blower ( 18 ) comprising the device ( 1 ) and the electronic circuit passing air stream, characterized by the steps of: a) transferring the electronic circuit from a first to a second state of activity or detecting such a change, b) detecting the temperature (T) of the electronic circuit in the second state of activity, c) Checking whether a temporal change of the temperature (T) is outside a predefined target range and d) triggering an alarm for a malfunction of the cooling or heating device if the result of the check is positive. A method according to claim 1, characterized in that in addition an ambient temperature is detected and the desired range depends on this. Method according to one of claims 1 to 2, characterized in that the steps b) to d) are carried out when the ambient temperature and / or the difference between the ambient temperature and the temperature (T) of the electronic circuit and / or one of the electronic circuit supplied power (P) at the beginning of the second state of activity is within a predeterminable range. Method according to one of claims 1 to 3, characterized in that in addition an air humidity and / or an air density of the air flow is detected and the desired range depends on this. Method according to one of claims 1 to 4, characterized in that the steps b) to d) are carried out when the air humidity and / or the air density of the air flow is within a predeterminable range. Method according to one of claims 1 to 5, characterized in that an electrical power (P), which is guided via said electronic circuit, is detected and the steps b) to d) are carried out when a temporal change of the power (P ) is detected beyond a predefinable threshold. Method according to one of claims 1 to 6, characterized in that said power (P) via the one energy converter ( 6 ) is detected for generating electrical current, which is fed through the electronic circuit, supplied power. Method according to one of claims 1 to 7, characterized in that step a) is carried out by activating or deactivating the electronic circuit. Method according to one of claims 1 to 8, characterized in that - the electronic circuit comprises at least one heat sink for temperature control of at least part of said circuit - the blower ( 18 ) generates an airflow passing through the heat sink and - that instead of the electronic circuit only the said circuit part is used for the inventive method. Method according to one of claims 1 to 9, characterized in that step a) by activating a in the circuit, in particular on the heat sink, arranged electrical heating element is performed. Method according to one of Claims 1 to 9, characterized in that step a) is carried out by transferring an inverter present in the circuit or formed by the circuit into an operation with adjustable power loss, in particular reactive power operation. Method according to one of claims 1 to 11, characterized in that a plurality of target ranges can be predetermined, each target range indicates an associated degree of disturbance of the cooling or heating device and wherein the alarm triggered when exceeding a certain target range information about the associated degree of disturbance contains. Method according to one of claims 1 to 12, characterized in that the alarm is transmitted via a mobile network and / or the Internet. Method according to one of claims 1 to 13, characterized in that an alarm is logged in a memory. Method according to one of claims 1 to 14, characterized in that in step d) another Checking the malfunction of the cooling or heating device is performed and only then alarm for a malfunction of the cooling or heating device is triggered when the result of both tests is positive. A method according to claim 15, characterized in that a power of the blower ( 18 ) with increasing deviation between setpoint and actual temperature of the device ( 1 ) and the further examination of the malfunction of the cooling or heating device comprises the steps: - detecting the performance of the fan ( 18 ) and - checking whether the parameter lies outside a predefinable target range (n _LV , n _MV , n _SV ). A method according to claim 15 or 16, characterized in that as the power of the blower ( 18 ) Characteristic parameter which is applied to a drive motor electrical voltage, the electrical current absorbed by a drive motor, the electrical power absorbed by a drive motor, the actual speed of a drive motor and / or the target speed of a drive motor is provided. A method according to claim 15, characterized in that a power loss of the device ( 1 ) and a performance descriptive parameter of the blower ( 18 ) is kept constant and the further examination of the malfunction of the cooling or heating device comprises the steps: - detecting the difference between the ambient temperature and the temperature of the electronic circuit and - checking whether the difference lies outside a predefinable target range comprises. Monitoring device ( 20 ) for a cooling or heating device, which for tempering a device ( 1 ) is provided with an electronic circuit, wherein the cooling or heating device is a blower ( 18 ), which for generating a device ( 1 ) as well as the electronic circuit passing air flow is prepared, characterized by - a switching device for transferring the electronic circuit from a first to a second state of activity and / or means for detecting such a change, - a temperature sensor ( 21 ) for detecting the temperature (T) of the electronic circuit in the second state of activity and means for checking whether a temporal change of the temperature (T) outside a predetermined target range and for triggering an alarm for a malfunction of the cooling or heating device, if the Result of the test is positive. Switch cabinet ( 14 . 14 ' ), comprising: - a device to be tempered ( 1 ) with an electronic circuit, - a blower ( 18 ), which is used to generate a control cabinet ( 14 . 14 ' ), the device ( 1 ) and the electronic circuit passing air flow, characterized by a monitoring device ( 20 ) according to claim 19. Switch cabinet ( 14 . 14 ' ) according to claim 20, characterized by a filter ( 17 ) in the flow of the air flow. Switch cabinet ( 14 . 14 ' ) according to claim 20 or 21, characterized in that - the electronic circuit comprises at least one heat sink for temperature control of at least part of said circuit - the fan ( 18 ) is prepared for generating an air stream passing through the heat sink and - the switching device is prepared for transferring said circuit part from a first to a second state of activity and / or means for detecting such a change are present. Switch cabinet ( 14 . 14 ' ), according to claim 22, characterized in that a temperature sensor ( 21 ) is arranged on the at least one heat sink. Switch cabinet ( 14 . 14 ' ) according to one of claims 20 to 23, characterized in that as an apparatus to be tempered an inverter ( 1 ) is provided. Switch cabinet ( 14 . 14 ' ) according to claim 24, characterized in that the circuit part to be tempered by at least one switching transistor or at least one switching thyristor of the inverter ( 1 ) is formed.

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