DE3515773A1 - Electronic fuse monitor - Google Patents

Abstract

According to the invention, the fuse monitor has a high-impedance path in parallel with the fuse insert, consisting of a PTC thermistor with a parallel resistor, a rectifier set and, on the DC-voltage side, a zener diode with a protection rectifier. The zener voltage supplies an optocoupler whose output is connected to an auxiliary power source and to the transistor switching section. The transistor switching section consists of switching transistors for emitting continuous pulses for remote signalling of the operating condition of the fuse inserts. In the case of a plurality of fuse inserts, the outputs of the optocouplers are connected in parallel. The changeover of the continous pulses for normal operation and a defect is carried out via transistors which influence the bases of the switching transistors. The continuous pulses for the respective operating condition are thus set automatically. Connected in parallel with the continuous pulse outputs are light-emitting diodes which indicate the operating condition. In addition, a light-emitting diode, which indicates a defect of the individual fuse insert, can be connected in parallel with each zener diode. A PTC thermistor in the input supply of the auxiliary power source prevents the switching transistors being overloaded. The fuse monitor is functional throughout the low-voltage range up to 440V DC or 660V AC voltage at high motor back-emfs and in the case of parallel cables, and is proof against short-circuits and resistant to switching voltage spikes.

Description

Electronic fuse monitoring.

The invention relates to a device, which the operating state by one or more fuse links, preferably 5 NH fuse links, monitored, and for normal operation, that means NH fuse link intact, as well as for the fault, that means fuse link blown, one continuous current pulse each time gives off to the outside. According to the invention, the device consists of a parallel path to the fuse link, which in the event of a fault

10 regardless of the voltage applied to the fuse link gives a constant current to the light emitting diode of an optocoupler, so that the switching transistor of the optocoupler on a transistor switching part switched through, which is fed by an auxiliary power source. In normal operation, the voltage on the fuse link is

15 voltage so low that the optocoupler does not switch through. The transistor part depending on the state of the optocoupler switches a continuous pulse either for normal operation or for a fault to the outside, whereby the other continuous pulse is switched off. Optionally, 2 light-emitting diodes are shown on the fuse monitoring device for direct display.

20 switches.

-§ The problems lie in the different network conditions

^ J and the shutdown behavior of a fuse link. The network can

^ 25 AC voltage or DC voltage, for AC voltage £ (three-phase current) up to 660V, for DC voltage up to 440V. When burned through

of a fuse link, e.g. with three-phase current, can occur as a result of the back EMF ζ of a large motor, but with fused parallel cables, the remains voltage on the fuse link must be very low compared to the mains voltage.

Λ 30 In the case of the fuse link, falsification of the fuse identification link ' ^{ω must} be avoided. In addition, when the fuse link J = J is switched off, a brief switching overvoltage that is several times higher than the mains voltage can occur.

P To date, the following designs are known to solve this problem: ο

κ 35 1.) The fuse link is one phase of a motor protection switch μ connected in parallel, whereby the overcurrent release device (usually w thermal bimetal) has a higher resistance, so that the motor

BATHROOM ORIGINAL - 2 -

circuit breaker is thus short-circuit proof and has relatively little influence on the fuse characteristic. For reporting or actuation of switching elements there is usually a break contact and a make contact in the motor protection switch. The motor protection switch is either designed for alternating current or direct current. The voltage required to operate the motor protection switch the blown fuse link is relatively low, but it is too high, for example, to be used on the fused Allow parallel cables. "Depending on the voltage applied to the fuse link in the event of a fault, it can take a few seconds to minutes take time until the motor protection switch switches. After eliminating the fault, the motor protection switch must be switched on again will.

2.) DE-OS 1933942. This circuit arrangement for electronic security monitoring is specially geared towards circuits for feeding several parallel connected, individually fused loads or converters with parallel connected valves, -π There is a diode provided with an RC circuit in ■ o series for every fuse link. The reverse voltage occurring during Sperrichtungs-I ^ 20 of the diode stress at Blown fuse link to ^ the fuse section is to transit £ a switch means located in the transistor used, the through-connection for switching a thyristor

leads, which is a visual display with a separate auxiliary

ω 25 voltage connects.

ό 3.) DE-OS 2533182. In this circuit arrangement for electronic Fuse monitoring, the fuse links are in parallel

S Diode branches that feed a common consumer

· § If one of the fuse links trips, it triggers because of the increased

30 current the other fuse links one after the other, whereby

χ the triggering of the first fuse is already registered wii. ,

w since each diode has an RC element connected in parallel, which means that the

w Signaling device during reverse-directional loading of the diode

receives power when the fuse link is ctarch burned. A separate one A control voltage source is not required, as the necessary energy is taken from the capacitor of the RC element will. Since the diodes with their RC element are connected to the network branches, is an application for the power supply of any consumer or directly connected to an alternating or three-phase network Consumer not possible.

4.) DE-OS 2831139. This arrangement for fuse monitoring has a light-emitting diode, connected in series with a PTC thermistor and a resistor connected in parallel with the PTC thermistor and parallel to the fuse link. A bridge rectifier can also be included in the series connection so that the light-emitting diode is then connected to the direct current output of the bridge rectifier. With this arrangement, it is not possible to carry out continuous pulses for remote reporting or remote control. There is no display for normal operation. Since the PTC thermistor with parallel resistance at maximum mains voltage must be adapted to the light-emitting diode in a cold state, the maximum permissible voltage of which is below 5V, and its resistance ^{increases significantly when the breakover current ■ - 1} 20 is exceeded, an insert, tj of the arrangement is despite the parallel resistance only possible in a limited line voltage range,

^ j The light-emitting diode is also endangered by switching overvoltages.

^ 5.) DE-OS 2851956. This arrangement for electronic fuse monitoring • j waehung has a parallel line to the fuse link,

j ^ - 25 standing from a rectifier diode, a glow lamp, a loading § limiting resistor and the light-emitting diode of an optocoupler, which are shown in

£ j are connected in series. If the fuse link is blown

P is the positive half-wave of the alternating

selvoltage through the rectifier diode and after the § 30 glow lamp let through the light-emitting diode of the optocoupler, Ί so that it switches through and a relay with the help of an auxiliary

t§ voltage actuated. The half-waves can be smoothed by

t £ a capacitor take place.

w 'In the event of a fault, the glow lamp provides an indicator light.

ώ 35 The arrangement results in a high response voltage in the event of a blowout

BATH

a fuse link because of the use of a glow lamp. In the lower voltage ranges or with secured It cannot be used with parallel cables. However, besides the motor protection switch, it is so far the only arrangement 5 "which is suitable for remote reporting or remote control. In contrast, the present invention is based on the object to create a fuse monitoring on an electronic basis, in the entire low-voltage network area, both at Alternating voltages up to 66QV three-phase current, as well as DC-10 voltages up to 440V, flawless monitoring of fuse links enabled, whereby in addition to the direct display on the device of the fuse monitoring also a remote message or remote control is secured for normal operation and for a malfunction. To be considered is the occurrence of short-circuit currents, a short-term switching overvoltage when a fuse link blows and compliance with the fuse characteristic. In the present invention, this is achieved in a simple manner in that the fuse link or fuse links one or more parallel lines can be connected, consisting of a series connection of a Zener diode with a protective rectifier diode, ^ a PTC thermistor with parallel resistance and a set of rectifiers

^ exist, where the line Zener diode with protective rectifier the

^ Light-emitting diode of an optocoupler, possibly with a series resistor

^ is connected in parallel.

g 25 During normal operation, only the voltage drop is present on the parallel section

£] case of the intact fuse link. This is not enough to

g to generate a voltage on the zener diode. This gives the entrance

of the optocoupler no voltage, its output remains blocked. At the

^ The fuse link can blow for a short time, a few ms long,

"P 30 a switching overvoltage occurs, of which the largest part on the cold

t§ conductor lies so that the rectifier for a smaller reverse voltage

J ₃ : can be interpreted. However, they must be designed for the corresponding J dt. After that, depending on the network conditions, there is a

tB lower or higher voltage on the blown fuse link

ORIGINAL! N3PZCTED

and the parallel path present, the Zener diode giving its fixed Zener voltage to the input of the optocoupler, its The output is switched through. As a result of this Zener voltage, it is also possible to have a parallel to the input of the optocoupler To switch the light-emitting diode, which indicates the stoning.

Since the PTC thermistor is exceeded depending on the voltage present Breakdown current increases its resistance only after seconds to minutes, the cold resistance of the PTC thermistor must be so high that the permissible continuous current of the rectifier set and the zener path is not exceeded. The optocoupler receives a constant input current as a result of the Zener voltage, as well as a .. possible parallel light-emitting diode. If you have to wait a long time Due to the increase in resistance of the PTC thermistor, a low current flows, maximum the breakover current. This current is enough but to maintain the Zener voltage due to the parallel resistance.

One output side of the optocoupler is connected to another PTC thermistor with low resistance, but a higher breakover current than the rated current for remote signaling and remote control, directly at a pole of an auxiliary DC voltage source. The other pole of the ^1-1 auxiliary voltage is connected to the collectors of two transistors, which cause the two switching transistors to be switched on for normal operation and malfunction. If there are several fuse links, the optocoupler outputs are connected in parallel. Due to the high in

^ 25 Dielectric strength due to the electrical isolation between

& The input and output of the optocoupler is opposite to the transistor part

ψ, mains voltage interruptions protected.

P When using NPN door locks and optocouplers, the

S Negative pole of the auxiliary voltage via the PTC thermistor directly to the

Emitters from the optocoupler and the switching transistors for normal

ro operation and malfunction as well as resistances at the base of these

S switching transistors. From the collectors of the switching transistors

ο the outputs for remote reporting and remote control go out.

κ Between the positive pole of the auxiliary voltage and these two

A light-emitting diode with a series resistor for direct display is located at each of the outputs the operating status.

During normal operation, a transistor for switching from the positive pole receives a positive voltage to the base via a resistor, it switches through and sends a positive voltage to the base of the switching transistor via a switching path and a resistor for normal operation. This positive voltage is higher than the fixed negative voltage from the minus pole that is applied via another resistor. The switching transistor then switches through for normal operation, and its collector output becomes negative. At the same time, it applies negative voltage to the base of the second switching transistor via a resistor. This is blocked so that a negative voltage on the switching transistor for the disturbance affects the base via a resistor from the minus pole, so that this switching transistor is blocked.
When the optocoupler is switched through, the first-mentioned switching transistor receives a negative voltage from the output of the optocoupler, it is blocked and thus the reverse switchover takes place. In the event of an overload or short circuit on the auxiliary voltage side - the breakover current of the KaIt- -H. conductor exceeded, so that the resistance of the PTC thermistor ο 20 increases and the overload is eliminated.

The invention is illustrated below with the aid of the

presented embodiment described in more detail. η The drawing shows three power lines leading to the consumer 1, 2 and 3. Fuse links 4 are located in these power lines,

S 25 and 6. As parallel lines to the fuse links are in series

w switched: PTC thermistors 10, 11 and 12 with parallel resistance 7, 8 and 9,

g Rectifier set 13, 14 and 15, Zener diode 16, 17 and 18, protective rectifier diode 19, 20 and 21.

Zener diode and protective rectifier diode are in parallel to the line

■ g 30 row the resistors 22, 23 and 24 with the optocoupler inputs 28,

E 29 and 30. LEDs 25, 26 and 27 can connect the optocoupler inputs

^ can be connected in parallel.

{^ The optocoupler outputs 31, 32 and 33 are connected in parallel. the

jij emitter side is connected from negative pole 50 to an auxiliary DC voltage source

ORJGfrML iN3Pc

fed a low-resistance PTC thermistor 44 and leads directly to Emitter of the switching transistor for normal operation 42 and above Switching path to the output for normal operation 51, as well as directly to the emitter of the switching transistor for the disturbance 40 and above

... 5 its switching path to the output for fault 52, also via Resistors 34 and 35 'to the base of the switching transistors 40 and 42, so that there is a negative bias voltage there. The collector side the optocoupler outputs 31, 32 and 33 leads directly to the base of the transistor 43, so that here when switching through an optocoupler

.10 results in a negative bias with which the transistor 43 is blocked. Since the base of the transistor 43 from the positive pole 49 of the auxiliary equilibrium voltage source with blocked optocouplers a positive Receives bias voltage via the resistor 39, it is switched through and gives a positive bias voltage via its switching path

. L5 resistor 38 on the base of the switching transistor 42, which is greater than the negative bias voltage via the resistor 35, so that the transistor 42 turns on and from its collector ^{gives a negative bias voltage via the resistor 37 to the base of the transistor 41 fH} , which thereby blocks so that at the switching transistor for the. ^ 20 disturbance 40 a negative base bias via the resistor 34

^ J is pending. The output for fault 52 is thus dead. When ^ switching through an optocoupler, the transistor 43 is blocked,

5! so that the positive bias of the base eliminates the SchalttrankJ ¹ sistors 42 via the resistor 38, the switching transistor for the standards

§3 25 maloperation 42 is blocked, output 51 is de-energized. Same- The negative biasing of the base of the transistor is eliminated in a timely manner g through resistor 37, transistor 41 turns on and gives

via its switching path to the base of the switching transistor for the i fault 40 a positive bias voltage across resistor 36, which is greater

"1 3.0 is greater than the negative bias voltage across resistor 34. So ü switches the switching transistor 40 through and the output 52 becomes negative, td For a visible display of the two switching states, between the cd positive pole 49 and the two outputs 51 and 52 light-emitting diodes 45 and ω with series resistors 47 and 48 connected.

If one of the switching transistors 40 and 42 is overloaded, the breakover? current of the PTC thermistor 44 exceeded, and the PTC thermistor 44 increases its resistance, so that the overload is eliminated. The drawing even representation of the switching device is divided g_ into the switch with fuses 53, the parallel route to the fuse links 54 and the transistor part of the 55th

^ ₁ ORIGINAL INSPECTED

Claims (7)

Claims 1. Arrangement for electronic monitoring of the operating status of fuse links in a consumer system in which consumers or parallel cables protected by fuses from a AC or DC voltage networks are fed, with each fuse link being assigned a high-resistance parallel line, which regardless of the level of the mains voltage when the fuse link blows, a constant DC voltage to one An optocoupler delivers that switches through the datiei and, with the help of an additional DC voltage source, one connected to it Alarm and control electronics operated, characterized in that the high-resistance parallel path to the fuse link is a Zener diode with protective rectifier diode, which is fed in via a bridge rectifier and a PTC thermistor with parallel resistance the -Zener diode in the event of a failure a constant 15 'delivers DC voltage to an optocoupler connected in parallel, which actuates a signaling and control electronics. 2. Arrangement still claim 1, characterized in that the reporting and control electronics are connected to a DC voltage source which, when the optocoupler is blocked, switches through a transistor or thyristor, which sends a continuous pulse to an output outputs, while when the optocoupler is switched through, another transistor or thyristor is switched through, which is on a second output supplies a continuous pulse, the second being blocked when one of the two transistors or thyristors responds will. 3. Arrangement according to claim 1 and 2, characterized in that between the two outputs of the reporting and control electronics and a light-emitting diode with a series resistor to display the two switching states is connected to the opposite pole of the DC voltage source is. 4. Arrangement according to claim 1 to 3, characterized in that each Line, consisting of Zener diode and protective rectifier diode, a light-emitting diode is connected in parallel, which burns the associated Fuse link. 5. Arrangement according to claim 1 to 4, characterized in that in the feed to the signaling and control electronics is connected to a PTC thermistor, which increases its resistance when the electronics are overloaded increases and thus eliminates the overload. 6. Arrangement according to claim 1 to 5, characterized in that it a multi-pole, preferably three-pole fuse monitoring is concerned, whose individual, high-resistance parallel lines to the fuse links are connected in parallel on the output side of the optocoupler are. 7. Arrangement according to claim 1 to 6, characterized in that the Fuse monitoring is arranged directly on a fuse disconnector.