RU2787414C2 - Method for control of cooling installation connected to electrical casing - Google Patents

Abstract

FIELD: refrigeration equipment.

SUBSTANCE: installation contains primary cooling circuit (C1), which contains condenser (COND1), at least one compressor (COMP1), and first evaporator (EV1); secondary cooling circuit (C2), which contains heat-insulated chamber (5), second evaporator (EV2) enclosed in mentioned heat-insulated chamber (5), air inlet (IN), and air outlet (OUT) with controlled opening/closing through the mentioned chamber, and fan (VENT2) placed with the possibility of creation of air circulation between the mentioned air inlet and the mentioned air outlet; PLC (20) made with the possibility of selection of an operating mode of the cooling installation from operating mode (MOD1), in which primary cooling circuit (C1) is active for cooling air present in an internal volume, and secondary cooling circuit (C2) charges its second evaporator (EV2) with cooling power, and second operating mode (MOD2), in which primary cooling circuit (C1) and secondary cooling circuit (C2) are simultaneously active for cooling air present in the mentioned internal volume. PLC is made with the possibility of acting as a module for selection of mentioned operating mode (MOD1), taking into account: dissipated heat power (Pth_D) in the internal volume of an electrical casing; heat power (Pth_EV1) of cooling, which first evaporator (EV1) is able to dissipate. First operating mode (MOD1) is selected by the mentioned PLC, when dissipated heat power (Pth_D) in the electrical casing is less than or equal to heat power (Pth_EV1), which the first evaporator is able to dissipate. Second operating mode (MOD2) is selected by PLC, when dissipated heat power (Pth_D) in the electrical casing is strictly greater than heat power (Pth_EV1), which the first evaporator is able to dissipate. The cooling installation contains a switching device adapted to switch the cooling installation between first operating mode (MOD1) and second operating mode (MOD2). PLC is made with the possibility of acting as a module for control of the mentioned switching device, taking into account the selected operating mode. The switching device is made with the possibility of connection of the secondary cooling circuit to the primary cooling circuit and maintenance of mentioned heat-insulated chamber (5) closed in the first operating mode.

EFFECT: energy losses are reduced.

10 cl, 7 dwg

Description

The field of technology to which the invention belongs

The present invention relates to a method for controlling a cooling plant used for cooling the interior of an electrical enclosure, such as an electrical cabinet, for example. The invention also relates to a cooling plant in which said method is implemented.

Description of the Prior Art

In the known method, with reference to FIG. 1, an electrical cabinet 1 contains electrical devices 3, some of which release heat during operation. The electrical cabinet 1 can therefore include a cooling unit 2 for cooling its interior and releasing heat to the outside. The cooling unit 2 in particular can integrate an air conditioner to cool the air inside the cabinet and exhaust the hot air to the outside.

In the known method, with reference to FIG. 2, the air conditioner is a thermodynamic machine to produce cold. It is essentially formed by two heat exchangers (EV evaporator and COND condenser) connected to a COMP compressor, all of which operate in a closed and pressurized circuit in which FF refrigerant circulates, which alternately becomes liquid or gaseous.

The air present in the electrical cabinet 1 is entrained and cooled in the evaporator EV in contact with the refrigerant FF, which becomes gaseous, before being redistributed into the internal volume of the cabinet 1. The FF refrigerant continues its journey as a vapor until it reaches the COMP compressor , which compresses the refrigerant through heating (at high pressure) and then sends it to the COND condenser. This capacitor extracts the calories from heating and releases them outside the electrical cabinet. Simultaneously, the fluid that is returned to liquid form (low pressure) is redirected to the evaporator EV, passing through the pressure reducer DET. This phase sequence is repeated as a cycle until the desired temperature is reached. The heat exchangers can be accelerated by means of a ventilation device and can be electronically controlled. As a simplification, the programmable logic controller (PLC) 20 of the plant receives the temperature setpoint T°cons and executes a temperature control loop based on the temperature T°amb measured in the electrical cabinet 1.

The components of such a refrigeration plant, in particular the compressor, are sized to take into account the maximum dissipated thermal power (expressed in W) that the electrical devices 3 present in the electrical cabinet can produce. However, it should be clear that this maximum thermal power is not reached. always or, otherwise, not continuously achieved. The COMP compressor of the refrigeration unit is then very often oversized in relation to the actual cooling requirements of the interior of the electrical cabinet, and the excess power it generates is then completely wasted.

The object of the invention is to provide a solution which makes it possible to avoid oversizing the cooling plant and eliminate energy losses when the dissipated heat power is not at its maximum.

The essence of the invention

This problem is solved by the method of controlling the installation for cooling the internal volume of the electric casing, containing:

- a primary refrigeration circuit which contains a condenser, at least one compressor and a first evaporator;

- a secondary cooling circuit that contains a thermally insulated chamber, a second evaporator placed in said thermally insulated chamber, an air inlet and an air outlet with controlled opening/closing through said chamber, and a fan arranged to circulate air between said air inlet and said air outlet;

- PLC configured to select the mode of operation of the refrigeration plant from at least one first operating mode, in which the primary refrigeration circuit is active to cool the air present in the interior space and the secondary refrigeration circuit charges the second evaporator with cooling power, and a second operating mode in which the primary cooling circuit and the secondary cooling circuit are active at the same time in order to cool the air present in said internal volume;

characterized in that it contains:

- the stage of choosing the said operating mode, taking into account:

- dissipated thermal power in the internal volume of the electrical casing;

- thermal power of cooling of the first evaporator;

wherein said first operating mode is selected by said PLC when the thermal power dissipated in the electrical cabinet is less than or equal to the thermal power that the first evaporator is capable of dissipating;

said second operating mode is selected by said PLC when the thermal power dissipated in the electrical cabinet is strictly greater than the thermal power that the first evaporator is capable of dissipating;

- a step in which said PLC controls the switching means configured to switch the refrigeration unit between the first operating mode and the second operating mode.

According to one feature, in the first operating mode, the switching means control step comprises:

- connecting the secondary cooling circuit to the primary cooling circuit and keeping said thermally insulated chamber closed.

According to another feature, in the second operating mode, the switching means control step comprises:

- disconnecting the secondary cooling circuit from the primary cooling circuit, opening the air inlet and outlet and turning on the fan to force air to circulate through the thermally insulated chamber.

According to another feature, the dissipated heat power is determined based on the difference between the set temperature value and the temperature value in the interior volume of the electric casing.

According to another feature, the heat output that the first evaporator is able to dissipate is determined when sizing the plant and then configured in the PLC.

The invention also relates to a device for cooling the internal volume of an electric casing, comprising:

- a primary refrigeration circuit which contains a condenser, at least one compressor and a first evaporator;

- a secondary cooling circuit that contains a thermally insulated chamber, a second evaporator placed in said thermally insulated chamber, an air inlet and an air outlet with controlled opening/closing through said chamber, and a fan arranged to circulate air between said air inlet and said air outlet;

- PLC configured to select the mode of operation of the refrigeration plant from at least one first operating mode, in which the primary refrigeration circuit is active to cool the air present in the interior space and the secondary refrigeration circuit charges the second evaporator with cooling power, and a second operating mode in which the primary cooling circuit and the secondary cooling circuit are active at the same time in order to cool the air present in said internal volume;

characterized in that:

- The PLC is configured to act as a module for selecting said operating mode, taking into account:

- dissipated thermal power in the internal volume of the electrical casing;

- the thermal power of cooling, which is able to dissipate the first evaporator;

wherein said first operating mode is selected by said PLC when the thermal power dissipated in the electrical cabinet is less than or equal to the thermal power that the first evaporator is capable of dissipating;

wherein said second operating mode is selected by said PLC when the thermal power dissipated in the electrical cabinet is strictly greater than the thermal power that the first evaporator is capable of dissipating;

- the cooling installation contains a switching means configured to switch the cooling installation between the first operating mode and the second operating mode;

- The PLC is configured to act as a module for controlling said switching means, taking into account the selected operating mode.

According to one feature, the switching means comprises a three-way valve capable of taking on at least two states: a first state in which the secondary refrigeration circuit is connected to the primary refrigeration circuit in the first operating mode, and a second state in which the secondary refrigeration circuit is disconnected from the primary refrigeration circuit. in the second operating mode.

According to another feature, the first evaporator is of a hybrid type with two independent cooling circuits, wherein the first cooling circuit belongs to the primary cooling circuit, and the second cooling circuit is connected to the secondary cooling circuit by means of a pump included in said switching means.

According to another feature, the dissipated heat power is determined based on the difference between the set temperature value and the temperature value in the interior volume of the electric casing.

According to another feature, the size in terms of thermal power dissipated from the second evaporator is larger than the size of the compressor.

In another feature, the heat output that the first evaporator is able to dissipate is determined during sizing and then configured in the PLC.

Brief description of the drawings

Additional features and advantages will become apparent from the detailed description below with reference to the accompanying drawings, which are listed below and in which:

Fig. 1 schematically shows an electrical cabinet to which a cooling unit is connected;

Fig. 2 schematically shows a refrigeration plant, for example a refrigeration plant, which is known in the art;

Fig. 3A and 3B schematically show two different embodiments of a refrigeration plant according to the invention;

Fig. 4 shows a diagram illustrating an algorithm implemented with the ability to control a refrigeration plant according to the invention;

Fig. 5A and 5B show the operation of the refrigeration plant according to the invention, respectively, when the first operating mode is active and when the second operating mode is active.

Reference numbers used in the accompanying drawings remain identical regardless of the drawing, provided the components retain identical function.

Detailed description of at least one embodiment

The invention is applicable to an installation 2 for improved cooling of an electrical enclosure, such as an electrical cabinet 1.

According to a specific aspect of the invention, plant 2 comprises a primary refrigeration circuit C1 and a secondary refrigeration circuit C2 connected to the primary refrigeration circuit.

The refrigeration plant 2 also includes a PLC 20 configured to control the primary refrigeration circuit C1 and the secondary refrigeration circuit C2. This PLC 20 traditionally contains a processing module, input modules and output modules. It may also contain a communication module for sending data to the central unit.

The primary cooling circuit C1 contains in particular the following components:

- air condenser COND1, which allows the transition of the refrigerant FF1 from a gaseous state to a liquid state. Air condenser COND1 can be tubular and finned or microchannel type, for example;

- pressure reducer DET1 to reduce the pressure of the FF1 refrigerant;

- the first evaporator EV1 for the transition of the refrigerant FF from the gas + liquid state to the gaseous state. The evaporator EV1 is designed for the passage of cooled air through it;

- one or more compressors COMP1, designed to suck in the refrigerant FF1 coming from the evaporator EV1 in the gaseous state in order to send it to the air condenser COND1;

- a plurality of fans VENT10 allowing air VENT1 to pass through the air condenser COND1 and through the first evaporator EV1 respectively;

- optionally, one or more circulation pumps;

- connecting pipes between different elements of the circuit.

The secondary cooling circuit C2 contains only:

- second evaporator EV2;

- a thermally insulated chamber 5, which houses the second evaporator EV2 and which contains at least one air inlet IN and one air outlet OUT with controlled opening/closing and which is connected to the PLC output modules 20;

at least one VENT2 fan connected to the PLC output module 20 allowing cooled air to circulate between the air inlet and air outlet when they are opened;

- at least one inlet pipe and one outlet pipe for circulation of the refrigerant FF2 in the secondary refrigeration circuit C2, connected to the inlet and outlet of the second evaporator and allowing the secondary refrigeration circuit to be connected to the primary refrigeration circuit C1.

Cooling plant 2 may also comprise a set of temperature sensors connected to PLC input modules, in particular:

- temperature sensor for measuring the medium temperature T°amb inside the electrical cabinet 1.

According to various specific aspects of the invention, the following principles may be followed:

- a complete sizing of the installation is carried out taking into account the maximum thermal power that the electrical devices 3 present in the electrical cabinet 1 are capable of dissipating and taking into account their duty cycle;

- the sizing in terms of thermal power dissipated from the second evaporator EV2 exceeds the sizing of the compressor COMP1. In other words, the heat output that can be dissipated by the second evaporator EV2 exceeds that of the compressor COMP1, which allows the installation to use a compressor that is undersized relative to the entire installation;

- the sizing of the COMP1 compressor (in terms of thermal output and therefore electrical output) depends on the duration of the complete charge cycle of the second evaporator EV2. In fact, it is important to ensure that the second EV2 can be sufficiently charged as quickly as possible, in particular during a slow duty cycle (i.e. when T°amb<T°cons) which is as short as possible (in terms of duration ). In this second situation, the first evaporator EV1 is not active and the entire capacity of the compressor COMP1 is dedicated to charging the second evaporator EV2;

- the second evaporator EV2 must be selected with a time constant that takes into account the most extreme temperature conditions for the operation of the plant. Once properly sized, the second evaporator must be able to provide peak load (ie high dissipation demand) at any given time. This time constant Sk is expressed using the following relationship:

Sk_EV2=(T°amb_max-T°EV2)/(Pth_EV2+Pth_EV1),

wherein

- Sk_EV2 corresponds to the time constant of the second evaporator;

- T°amb_max corresponds to the maximum ambient temperature to which the internal volume of the electrical cabinet can be exposed;

- T°EV2 corresponds to the temperature of the second evaporator EV2.

Based on the input data that is received, and by executing the program for controlling the cooling unit, the PLC 20 determines the thermal power dissipation Pth_D in the electrical cabinet.

In addition, the PLC predominantly knows the following data:

- the maximum heat output Pth_EV1 that the first evaporator EV1 is able to dissipate, which data can be entered as a parameter;

- the maximum heat output Pth_EV2 that the second evaporator EV2 is capable of dissipating, which data can be entered as a parameter.

It should be noted that the PLC 20 can also implement known control algorithms, such as those disclosed in patent application EP 2759786 A1. These algorithms provide the ability to determine all the thermal and electrical data of the cooling plant based on measurements and data on the operating status of the various components of the plant.

The PLC 20 is configured to execute an operating mode from the following two different operating modes:

- the first operating mode MOD1 is executed by the PLC when the dissipated heat power Pth_D in the electrical cabinet 1 is less than or equal to the heat power Pth_EV1 that the first evaporator EV1 is able to dissipate;

- the second operating mode MOD2 is executed by the PLC when the dissipated heat power Pth_D in the electrical cabinet 1 is strictly greater than the heat power Pth_EV1 that the first evaporator EV1 is able to dissipate.

In the first operating mode MOD1, since the primary refrigeration circuit C1 is sized to operate up to the maximum power, the excess power generated during operation (i.e., the excess power of the compressor COMP1 which is not used by the first evaporator EV1) is used in order to cold charge the second EV2 coil. Therefore, the secondary refrigeration circuit C2 is connected to the primary refrigeration circuit C1 to use the energy available in the primary refrigeration circuit C1 to charge its evaporator EV2.

In the second operating mode MOD2, the first evaporator EV1 is not sufficient to dissipate the thermal power Pth_d generated by the devices 3 present in the electrical cabinet 1. Therefore, the secondary cooling circuit C2 is activated in order to dissipate the additional thermal power that the first evaporator EV1 cannot dissipate. In this operating mode, the second evaporator does not require compressor power. The first evaporator EV1 is predominantly used to its maximum potential.

The refrigeration plant 2 therefore comprises switching means which are controlled by the PLC 20 and are connected to the output modules. These switching means are configured to ensure that the plant switches between the first operating mode MOD1 and the second operating mode MOD2. These switching means are controlled by the PLC 20 when it selects the first operating mode or the second operating mode.

In the first operating mode MOD1, the switching means ensures that the secondary refrigeration circuit C2 is connected to the primary refrigeration circuit C1. The primary cooling circuit C1 is active for cooling the air present in the electrical cabinet, and the secondary cooling circuit C2 is then in charge mode. Then, the air inlet IN and air outlet OUT of the chamber 5, which contains the second evaporator EV2, is controlled to close, and the fan VENT2 is inactive to store cooling energy in the second evaporator EV2.

In the second operating mode MOD2, the switching means ensures that the secondary refrigeration circuit C2 is disconnected from the primary refrigeration circuit C1. The air inlet IN and the air outlet OUT of the chamber 5, which contains the second evaporator EV2, are controlled to open, and the fan VENT2 is turned on (activated) to circulate cool air in contact with the second evaporator EV2. Thus, both cooling circuits C1, C2 are active.

With reference to FIG. 3A, in the first embodiment, the switching means may comprise a three-way valve 6 which may assume at least the following two states:

- in the first state, it connects the secondary refrigeration circuit C2 to the primary refrigeration circuit C1, and then the second evaporator EV2 is connected in series with the first evaporator EV1; this state is activated in the first operating mode MOD1 of the plant;

- in the second state, it ensures that the secondary cooling circuit C2 is disconnected from the primary cooling circuit C1; this state is activated in the second operating mode MOD2 of the plant.

With reference to FIG. 3B, in the second embodiment, the switching means comprises a pump P2. The first evaporator EV1 of the primary cooling circuit is then of the hybrid type, i. e. it comprises a first refrigeration circuit integrated in the primary refrigeration circuit and a second refrigeration circuit independent of this first refrigeration circuit and connected to the secondary refrigeration circuit and therefore also to the second evaporator EV2. Pump P2 is placed on the secondary cooling circuit C2. In the first operating mode MOD1, the pump P2 is active, thereby circulating the refrigerant FF2 from the first evaporator EV1 to the second evaporator and therefore storing cooling energy in the second evaporator EV2 when the dissipated heat power in the electrical cabinet is less than the heat power that can be dissipated first evaporator EV1. The pump is deactivated in the second operating mode MOD2 in order to disconnect the secondary cooling circuit C2 from the primary cooling circuit C1 and therefore use the secondary cooling circuit in order to supplement the primary cooling circuit with respect to the cooling of the air present in the electrical cabinet 1.

With reference to FIG. 4, the algorithm executed by the PLC to determine the applicable operating mode is as follows:

E1: The PLC receives the temperature setpoint T°cons to be maintained in the interior of the electrical cabinet and the measured temperature T°amb measured in the electrical cabinet. The PLC compares the set value with the temperature value in the interior of the electrical cabinet to determine the heat dissipation Pth_D in the electrical cabinet;

E2: Based on the detected thermal power dissipation Pth_D, the PLC 20 compares it with the maximum thermal power Pth_EV1 that the first evaporator EV1 can dissipate. This heat output Pth_EV1 is determined when sizing the system and is entered as a parameter;

E3: if the dissipated heat power Pth_D is less than or equal to the heat power Pth_EV1 that the first evaporator EV1 can dissipate, then the PLC selects the first operation mode MOD1. The air is thereby cooled by the first evaporator EV1 and the second evaporator EV2 is charged with the remaining excess energy;

E4: If the dissipated heat power Pth_D exceeds the heat power Pth_EV1 that the first evaporator EV1 can dissipate, then the PLC selects the second operating mode MOD2. The air is therefore cooled by the first evaporator EV1 and the second evaporator EV2 at the same time. The chamber 5 of the second evaporator is open and the fan VENT2 is turned on so as to circulate the air;

E5: The second operating mode MOD2 may remain active provided that the thermal power dissipation Pth_D does not fall below the threshold value S1 for a given duration Tx (eg 5 minutes).

When the second operating mode is selected, the algorithm may also comprise the step of checking that the second evaporator EV2 has sufficient cooling capacity to cover the shortage of the first evaporator EV1. In such a case, it includes comparing the heat power Pth_EV2 that the second evaporator EV2 is able to dissipate with the difference between the heat power dissipation Pth_D and the heat power Pth_EV11 that the first evaporator is able to dissipate. If the capacity of the second evaporator EV2 is not sufficient, the unit may be placed in a default state and the PLC 20 may need to send a command to stop the electrical devices.

Fig. 5A and 5B show, based on the first embodiment described above, the operating principle of the plant in the first operating mode MOD1 and in the second operating mode MOD2, respectively.

In FIG. 5A, the electrical devices 3 present in the electrical cabinet 1 generate a dissipated heat power Pth_D which is 200 W. The primary cooling circuit is capable of dissipating 1000 W of thermal power. The first evaporator EV1 must therefore dissipate 200 W of thermal power Pth_EV1, while the remaining 800 W are used to charge the second evaporator. In FIG. 5A, valve 6 is controlled to connect the secondary refrigeration circuit to the primary refrigeration circuit. Then the second evaporator EV2 will be connected in series with the first evaporator EV1. The refrigerant then circulates through the first evaporator EV1 and then through the second evaporator.

In FIG. 5B, the electrical devices 3 present in the electrical cabinet generate a heat dissipation power Pth_D which is 3000 W. The primary cooling circuit is capable of dissipating 1000 W of thermal power. The first evaporator EV1 must therefore dissipate 1000 W of thermal power Pth_EV1. The secondary cooling circuit C2 is activated to dissipate the remaining 2000 watts. The second evaporator EV2 must therefore dissipate 2000 W of thermal power Pth_EV2. In FIG. 5B, valve 6 is controlled to disconnect the secondary refrigeration circuit from the primary refrigeration circuit. The second evaporator EV2 is then disconnected from the first evaporator EV1. Air inlet IN and air outlet OUT open. The VENT2 fan is activated to allow air to circulate through the second EV2.

From the above, it is clear that the solution according to the invention has many advantages, such as:

- it provides for limiting energy losses when the unit is in the first operating mode, when using excess energy in order to charge the second EV2 evaporator;

- it allows you to cope with peak loads with the help of a secondary cooling circuit;

- it overcomes all operational faults or breakdowns in the primary refrigeration circuit. In fact, it is still possible to independently activate the secondary cooling circuit in order to cool the air present in the electrical cabinet while the primary cooling circuit is inactive (for various reasons: intentional or unintentional);

- it is simple to implement. In fact, all that is required is the connection of the secondary refrigeration circuit to the primary refrigeration circuit and the introduction of switching means adapted therefor.

Claims (34)

1. A method for controlling an installation for cooling the internal volume of an electric casing, containing: a primary refrigeration circuit (C1) which contains a condenser (COND1), at least one compressor (COMP1) and a first evaporator (EV1); - a secondary cooling circuit (C2) which contains a thermally insulated chamber (5), a second evaporator (EV2) enclosed in said thermally insulated chamber (5), air inlet (IN) and air outlet (OUT) with controlled opening/closing through said chamber and a fan (VENT2) disposed to circulate air between said air inlet and said air outlet; - PLC (20) configured to select the operation mode of the cooling plant from at least one first operating mode (MOD1), in which the primary cooling circuit (C1) is active for cooling the air present in the internal volume, and the secondary circuit (C2 ) cooling charges its second evaporator (EV2) with cooling power, and a second operating mode (MOD2) in which the primary cooling circuit (C1) and the secondary cooling circuit (C2) are active at the same time to cool the air present in said interior space; - moreover, the mentioned method is characterized in that it contains: - the step of selecting the mentioned operating mode (MOD1) taking into account: - dissipated thermal power (Pth_D) in the internal volume of the electrical enclosure; - thermal power (Pth_EV1) for cooling the first evaporator (EV1); wherein said first operating mode (MOD1) is selected by said PLC when the dissipated thermal power (Pth_D) in the electrical enclosure is less than or equal to the thermal power (Pth_EV1) that the first evaporator (EV1) is able to dissipate; said second operating mode (MOD2) is selected by said PLC when the dissipated thermal power (Pth_D) in the electrical enclosure is strictly greater than the thermal power (Pth_EV1) that the first evaporator (EV1) is able to dissipate; - a step in which said PLC (20) controls a switching means adapted to switch the refrigeration plant between a first operating mode (MOD1) and a second operating mode (MOD2), wherein in the first operating mode the step of controlling the switching means comprises: - connecting the secondary cooling circuit to the primary cooling circuit and keeping said thermally insulated chamber (5) closed. 2. The method according to claim 1, characterized in that in the second operating mode, the step of controlling the switching means comprises: - disconnecting the secondary cooling circuit from the primary cooling circuit, opening the air inlet and outlet and turning on the fan (VENT2) to force air to circulate through the thermally insulated chamber (5). 3. The method according to any one of paragraphs. 1, 2, characterized in that the dissipated thermal power (Pth_D) is determined based on the difference between the set temperature value (T°cons) and the temperature value (T°amb) in the internal volume of the electrical casing. 4. The method according to any one of paragraphs. 1-3, characterized in that the heat output (Pth_EV1) that the first evaporator (EV1) is able to dissipate is determined when sizing the plant and then configured in the PLC (20). 5. Installation for cooling the internal volume of the electrical casing, containing: a primary refrigeration circuit (C1) which contains a condenser (COND1), at least one compressor (COMP1) and a first evaporator (EV1); - a secondary cooling circuit (C2) which contains a thermally insulated chamber (5), a second evaporator (EV2) enclosed in said thermally insulated chamber (5), air inlet (IN) and air outlet (OUT) with controlled opening/closing through said chamber and a fan (VENT2) disposed to circulate air between said air inlet and said air outlet; - PLC (20) configured to select the operation mode of the cooling plant from at least one first operating mode (MOD1), in which the primary cooling circuit (C1) is active for cooling the air present in the internal volume, and the secondary circuit (C2 ) cooling charges its second evaporator (EV2) with cooling power, and a second operating mode (MOD2) in which the primary cooling circuit (C1) and the secondary cooling circuit (C2) are active at the same time to cool the air present in said interior space; characterized in that: - PLC is configured to act as a module for selecting said operating mode (MOD1) considering: - dissipated thermal power (Pth_D) in the internal volume of the electrical enclosure; - thermal power (Pth_EV1) cooling, which is able to dissipate the first evaporator (EV1); wherein said first operating mode (MOD1) is selected by said PLC when the dissipated thermal power (Pth_D) in the electrical enclosure is less than or equal to the thermal power (Pth_EV1) that the first evaporator is able to dissipate; said second operating mode (MOD2) is selected by said PLC when the thermal power dissipated (Pth_D) in the electrical enclosure is strictly greater than the thermal power (Pth_EV1) that the first evaporator is able to dissipate; - moreover, the cooling installation contains a switching means adapted to switch the cooling installation between the first operating mode (MOD1) and the second operating mode (MOD2); - the PLC is configured to act as a module for controlling said switching means, taking into account the selected operating mode, and the switching means is configured to connect the secondary cooling circuit to the primary cooling circuit and keep said heat-insulated chamber (5) closed in the first operating mode. 6. Installation according to claim 5, characterized in that the switching means comprises a three-way valve capable of taking on at least two states: the first state in which the secondary cooling circuit (C2) is connected to the primary cooling circuit (C1) in the first operating mode ( MOD1), and a second state in which the secondary refrigeration circuit (C2) is disconnected from the primary refrigeration circuit in the second operating mode (MOD2). 7. Plant according to claim 5, characterized in that the first evaporator (EV1) is of a hybrid type with two independent cooling circuits, wherein the first cooling circuit belongs to the primary cooling circuit (C1) and the second cooling circuit is connected to the secondary cooling circuit by means of a pump (P2) included in said switching means. 8. Installation according to any one of paragraphs. 5-7, characterized in that the dissipated thermal power (Pth_D) is determined based on the difference between the temperature setpoint (T°cons) and the temperature value (T°amb) in the internal volume of the electrical casing. 9. Installation according to any one of paragraphs. 5-8, characterized in that the size in terms of thermal power dissipated from the second evaporator (EV2) is larger than the size of the compressor (COMP1). 10. Installation according to any one of paragraphs. 5-8, characterized in that the thermal power (Pth_EV1) that the first evaporator (EV1) is able to dissipate is determined during sizing and then configured in the PLC (20).

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