Control circuit of environmental test chamber with semiconductor refrigeration dehumidification function

Abstract

The utility model provides a kind of environmental test chamber control circuit with semiconductor refrigeration dehumidification function, including main controller U1, contactor KM1, contactor KM2, contactor KM4, relay KA1, relay KA2, relay KA5, frequency converter VFD1, phase sequence protector KVS1, air switch CP1, and semiconductor refrigeration module ZL1 and semiconductor refrigeration fan M2 etc.;Frequency converter VFD1 can control the rotating speed of semiconductor refrigeration fan M2;The utility model can reduce the starting frequency and running time of compressor when the temperature in environmental test chamber is above 0 DEG C and accurate temperature control is needed by the auxiliary semiconductor refrigeration dehumidification function, to improve the service life of compressor and reduce energy consumption.

Description

Technical Field

[0001] This utility model relates to an environmental test chamber, and more particularly to an environmental test chamber with semiconductor refrigeration and dehumidification function. Background Technology

[0002] Environmental test chambers have a wide range of applications, including in universities and corporate R&D departments. By adjusting the internal temperature and humidity, environmental test chambers allow products to undergo environmental simulation experiments in a short period of time, thus verifying their performance.

[0003] Environmental test chambers contain many electronic components, making it essential to design a fully functional control circuit.

[0004] In addition, environmental test chambers typically use compressors to control temperature. When the temperature inside the environmental test chamber is above 0°C, frequent compressor starts can affect the lifespan of the chamber if precise temperature control is required. Furthermore, prolonged compressor operation leads to high energy consumption. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this utility model provides a control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification functions. This circuit reduces the frequency of compressor starts and operating time when the temperature inside the environmental test chamber is above 0°C and precise temperature control is required, thereby improving compressor lifespan and reducing energy consumption. To achieve the above technical objectives, the technical solution adopted by this utility model is as follows: This utility model embodiment provides a control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification function, including a main controller U1, contactors KM1, KM2, KM4, relays KA1, KA2, KA5, frequency converter VFD1, phase sequence protector KVS1, and air switch CP1. One side of the three-phase normally open contact KM2-1 of contactor KM2 is connected to the three-phase live wires R0, S0, and T0, and the other side is connected to the condenser fan M1; one end of the main compressor CM1 is connected to one phase on the other side of the three-phase normally open contact KM2-1 of contactor KM2, and the other end is connected to the neutral wire N0. The input side of the frequency converter VFD1 is connected to the three-phase live wires R0, S0, and T0, and the output side is connected to one side of the three-phase normally open contact KM4-1 of the contactor KM4. The other side of the three-phase normally open contact KM4-1 of the contactor KM4 is connected to the semiconductor refrigeration fan M2. The input side of the phase sequence protector KVS1 is connected to the three-phase live wires R0, S0, and T0, and its detection terminal is connected to the live wire T0; the output terminal of the phase sequence protector KVS1 is connected to one end of the air switch CP1, and the other end of the air switch CP1 and the neutral line N0 provide AC voltage to the main controller U1. One end of the emergency stop switch SBE1 is connected to the AC voltage output from the output terminal of the phase sequence protector KVS1, and the other end is connected to one end of the start switch SB1. The other end of the start switch SB1 is connected to the AC common terminal of the main controller U1. One end of the normally open contact SUB1 for panel over-temperature detection is connected to input terminal X1 of main controller U1, and the other end is connected to the common input terminal of main controller U1; one end of the normally open contact ST2 for humidifier dry burning detection is connected to input terminal X11 of main controller U1, and the other end is connected to the common input terminal of main controller U1; one end of the normally open contact SL3 for water tank water shortage detection is connected to input terminal X12 of main controller U1, and the other end is connected to the common input terminal of main controller U1. The output terminal Y1 of the main controller U1 is connected to one end of the coil of contactor KM1, and the other end of the coil of contactor KM1 is connected to the neutral line N0; The output terminal Y2 of the main controller U1 is connected to one end of the normally open contact SL1 for water tank replenishment detection. The other end of the normally open contact SL1 for water tank replenishment detection is connected to one end of the normally open contact SL2 for water tank replenishment detection and one end of the normally open contact KA1-1 of relay KA1. The other end of the normally open contact SL2 for water tank replenishment detection and the other end of the normally open contact KA1-1 of relay KA1 are connected to one end of the coil of relay KA1. The other end of the coil of relay KA1 is connected to the neutral line N0. The normally open contacts SL1, SL2, and SL3 for water tank shortage detection are all float switches, which close when there is a water shortage and are located in the upper, middle, and lower positions of the water tank, respectively. One end of the normally open contact KA1-2 of relay KA1 is connected to the positive voltage VCC1, and the other end is connected to one end of the water supply pump M3. The other end of the water supply pump M3 is connected to 0V. The output terminal Y3 of the main controller U1 is connected to one end of the coil of contactor KM2, and the other end of the coil of contactor KM2 is connected to the neutral line N0. The output terminals Y4, Y5 and Y6 of the main controller U1 are connected to one end of solenoid valve NEU1, one end of solenoid valve NEU2 and one end of solenoid valve NEU3 respectively. The other ends of solenoid valve NEU1, solenoid valve NEU2 and solenoid valve NEU3 are connected to one end of normally open contact KM2-2 of contactor KM2. The other end of normally open contact KM2-2 of contactor KM2 is connected to neutral line N0. The output terminal Y7 of the main controller U1 is connected to one end of the coil of contactor KM4 and one end of the coil of relay KA5. The other end of the coil of contactor KM4 and the other end of the coil of relay KA5 are connected to the neutral line N0. One end of the normally open contact KA5-1 of relay KA5 is connected to the positive voltage VCC3, and the other end is connected to one end of the semiconductor refrigeration module ZL1. The other end of the semiconductor refrigeration module ZL1 is connected to 0V. The refrigeration side of the semiconductor refrigeration module ZL1 is equipped with a semiconductor refrigeration dehumidification pipeline and a semiconductor refrigeration fan M2. The output terminal Y8 of the main controller U1 is connected to one end of the solenoid valve NEU4. The other end of the solenoid valve NEU4 is connected to one end of the normally open contact KM4-2 of the contactor KM4. The other end of the normally open contact KM4-2 of the contactor KM4 is connected to the neutral line N0.

[0006] Furthermore, the control circuit of the environmental test chamber with semiconductor refrigeration and dehumidification function also includes a power indicator light HL1. One end of the power indicator light HL1 is connected to the AC common terminal of the main controller U1, and the other end is connected to the neutral line N0.

[0007] Furthermore, the control circuit of the environmental test chamber with semiconductor refrigeration and dehumidification function also includes relays KA2 and KA3; The output terminal Y2 of the main controller U1 is connected to one end of the coil of relay KA2, and the other end of the coil of relay KA2 is connected to the neutral line N0; one end of the normally open contact KA2-1 of relay KA2 is connected to the positive voltage VCC1, and the other end is connected to one end of the panel heater L2, and the other end of the panel heater L2 is connected to 0V. The output terminal Y11 of the main controller U1 is connected to one end of the coil of relay KA3, and the other end of the coil of relay KA3 is connected to the neutral line N0; one end of the normally open contact KA3-1 of relay KA3 is connected to the positive voltage VCC1, and the other end is connected to one end of the external heater L3 on the panel, and the other end of the external heater L3 on the panel is connected to 0V.

[0008] Furthermore, the control circuit of the environmental test chamber with semiconductor refrigeration and dehumidification function also includes a relay SSRM; the output terminal Y11 of the main controller U1 is connected to one end of the relay SSRM coil, and the other end of the relay SSRM coil is connected to the neutral line N0; one end of the normally open contact SSRM-1 of the relay SSRM is connected to the live line T0, and the other end is connected to one end of the door frame heating cable L1, and the other end of the door frame heating cable L1 is connected to the neutral line N0.

[0009] Furthermore, the control circuit of the environmental test chamber with semiconductor refrigeration and dehumidification function also includes a relay KA4. The output terminal Y12 of the main controller U1 is connected to one end of the coil of the relay KA4, and the other end of the coil of the relay KA4 is connected to the neutral line N0. One end of the normally open contact KA4-1 of the relay KA4 is connected to the positive voltage VCC2, and the other end is connected to one end of the lighting lamp HL3, and the other end of the lighting lamp HL3 is connected to 0V.

[0010] The beneficial effects of the technical solution provided by this utility model embodiment are: 1) The control functions are complete, meeting the control requirements of the environmental test chamber.

[0011] 2) Through the auxiliary semiconductor cooling and dehumidification function, when the temperature inside the environmental test chamber is above 0℃ and precise temperature control is required, the frequency of compressor start-up and running time can be reduced, thereby improving the compressor's service life and reducing energy consumption. Attached Figure Description

[0012] Figure 1 This is the first part of the circuit diagram in the embodiment of this utility model.

[0013] Figure 2 This is the second part of the circuit diagram in the embodiment of this utility model.

[0014] Figure 3 This is the third part of the circuit diagram in the embodiment of this utility model. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0016] like Figure 1 , Figure 2 and Figure 3 As shown in the figure, the control circuit of the environmental test chamber with semiconductor refrigeration and dehumidification function proposed in this utility model embodiment includes a main controller U1, contactors KM1, KM2, KM4, relays KA1, KA2, KA5, frequency converter VFD1, phase sequence protector KVS1, and air switch CP1. One side of the three-phase normally open contact KM2-1 of contactor KM2 is connected to the three-phase live wires R0, S0, and T0, and the other side is connected to the condenser fan M1; one end of the main compressor CM1 is connected to one phase on the other side of the three-phase normally open contact KM2-1 of contactor KM2, and the other end is connected to the neutral wire N0. The input side of the frequency converter VFD1 is connected to the three-phase live wires R0, S0, and T0, and the output side is connected to one side of the three-phase normally open contact KM4-1 of the contactor KM4. The other side of the three-phase normally open contact KM4-1 of the contactor KM4 is connected to the semiconductor refrigeration fan M2. The input side of the phase sequence protector KVS1 is connected to the three-phase live wires R0, S0, and T0, and its detection terminal is connected to the live wire T0; the output terminal of the phase sequence protector KVS1 is connected to one end of the air switch CP1, and the other end of the air switch CP1 and the neutral line N0 provide AC voltage to the main controller U1; the AC voltage output by the output terminal of the phase sequence protector KVS1 is AC220V. One end of the emergency stop switch SBE1 is connected to the AC voltage output from the output terminal of the phase sequence protector KVS1, and the other end is connected to one end of the start switch SB1. The other end of the start switch SB1 is connected to the AC common terminal of the main controller U1. One end of the normally open contact SUB1 for panel over-temperature detection is connected to input terminal X1 of main controller U1, and the other end is connected to the common input terminal of main controller U1; one end of the normally open contact ST2 for humidifier dry burning detection is connected to input terminal X11 of main controller U1, and the other end is connected to the common input terminal of main controller U1; one end of the normally open contact SL3 for water tank water shortage detection is connected to input terminal X12 of main controller U1, and the other end is connected to the common input terminal of main controller U1. The output terminal Y1 of the main controller U1 is connected to one end of the coil of contactor KM1, and the other end of the coil of contactor KM1 is connected to the neutral line N0; contactor KM1 is used for overall operation control; The output terminal Y2 of the main controller U1 is connected to one end of the normally open contact SL1 for water tank replenishment detection. The other end of the normally open contact SL1 for water tank replenishment detection is connected to one end of the normally open contact SL2 for water tank replenishment detection and one end of the normally open contact KA1-1 of relay KA1. The other end of the normally open contact SL2 for water tank replenishment detection and the other end of the normally open contact KA1-1 of relay KA1 are connected to one end of the coil of relay KA1. The other end of the coil of relay KA1 is connected to the neutral line N0. The normally open contacts SL1, SL2, and SL3 for water tank shortage detection are all float switches, which close when there is a water shortage and are located in the upper, middle, and lower positions of the water tank, respectively. One end of the normally open contact KA1-2 of relay KA1 is connected to the positive voltage VCC1, and the other end is connected to one end of the water supply pump M3. The other end of the water supply pump M3 is connected to 0V. The output terminal Y3 of the main controller U1 is connected to one end of the coil of contactor KM2, and the other end of the coil of contactor KM2 is connected to the neutral line N0. The output terminals Y4, Y5, and Y6 of the main controller U1 are connected to one end of solenoid valve NEU1, one end of solenoid valve NEU2, and one end of solenoid valve NEU3, respectively. The other ends of solenoid valves NEU1, NEU2, and NEU3 are connected to one end of the normally open contact KM2-2 of contactor KM2. The other end of the normally open contact KM2-2 of contactor KM2 is connected to the neutral line N0. Solenoid valves NEU1, NEU2, and NEU3 are used to control the on / off of pipelines related to the main compressor CM1. The output terminal Y7 of the main controller U1 is connected to one end of the coil of contactor KM4 and one end of the coil of relay KA5. The other end of the coil of contactor KM4 and the other end of the coil of relay KA5 are connected to the neutral line N0. One end of the normally open contact KA5-1 of relay KA5 is connected to the positive voltage VCC3, and the other end is connected to one end of the semiconductor refrigeration module ZL1. The other end of the semiconductor refrigeration module ZL1 is connected to 0V. The refrigeration side of the semiconductor refrigeration module ZL1 is equipped with a semiconductor refrigeration dehumidification pipeline and a semiconductor refrigeration fan M2. The heating side of the semiconductor refrigeration module ZL1 can face outwards from the environmental test chamber and is equipped with a heat sink and a cooling fan. The output terminal Y8 of the main controller U1 is connected to one end of the solenoid valve NEU4, and the other end of the solenoid valve NEU4 is connected to one end of the normally open contact KM4-2 of the contactor KM4. The other end of the normally open contact KM4-2 of the contactor KM4 is connected to the neutral line N0. The solenoid valve NEU4 is used to control the on / off of the semiconductor refrigeration dehumidification pipeline.

[0017] After pressing the start switch SB1 to turn on the environmental test chamber, the contactor KM1 coil in the environmental test chamber is energized, and the environmental test chamber starts to run. After the contactor KM2 coil is energized, the main compressor CM1 and the condenser fan M1 run, and the environmental test chamber begins to cool. When the temperature inside the environmental test chamber drops to a target temperature above 0℃, it can switch to semiconductor refrigeration dehumidification mode. At this time, the contactor KM2 coil can be de-energized, which energizes the contactor KM4 coil and the relay KA5 coil. The three-phase normally open contact KM4-1 of the contactor KM4 closes, and the semiconductor refrigeration fan M2 starts to work. The speed of the semiconductor refrigeration fan M2 can be controlled by the frequency converter VFD1. The normally open contact KM4-2 of the contactor KM4 closes, and the semiconductor refrigeration dehumidification pipeline can be controlled to conduct by opening the solenoid valve NEU4. The normally open contact KA5-1 of the relay KA5 closes, and the semiconductor refrigeration module ZL1 works, producing a cooling effect on its cooling side. Since the environmental test chamber can maintain its internal temperature at the target temperature after reaching a temperature above 0°C, it only needs to use the semiconductor refrigeration module ZL1 to maintain the target temperature, so there is no need to frequently start and stop the main compressor CM1, which improves the compressor's service life and reduces energy consumption.

[0018] When the water level in the tank is low, the normally open contacts SL1 and SL2 for water tank replenishment detection close sequentially, energizing the coil of relay KA1. Relay KA1's normally open contact KA1-1 closes and holds, while relay KA1's normally open contact KA1-2 closes, activating the water replenishment pump M3. When the water level in the tank exceeds the levels of SL1 and SL2, these contacts open sequentially, de-energizing relay KA1 and causing relay KA1's normally open contact KA1-2 to open, stopping the water replenishment pump M3. In cases of extreme water shortage, such as when water pump M3 malfunctions, the normally open contact SL3 for water shortage detection closes, sending an alarm signal to the main controller U1, allowing it to take appropriate safety measures.

[0019] The normally open contact SUB1 for panel overheat detection and the normally open contact ST2 for humidifier dry burning detection can also send alarm signals to the main controller U1, so that panel heating is stopped when the panel overheats and the humidifier is prevented from dry burning.

[0020] Furthermore, an environmental test chamber control circuit with semiconductor refrigeration and dehumidification function also includes a power indicator light HL1, one end of which is connected to the AC common terminal of the main controller U1, and the other end is connected to the neutral line N0.

[0021] Furthermore, a control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification function also includes relays KA2 and KA3; The output terminal Y2 of the main controller U1 is connected to one end of the coil of relay KA2, and the other end of the coil of relay KA2 is connected to the neutral line N0; one end of the normally open contact KA2-1 of relay KA2 is connected to the positive voltage VCC1, and the other end is connected to one end of the heater L2 inside the panel, and the other end of the heater L2 inside the panel is connected to 0V; the environmental test chamber is equipped with a glass panel, and heaters are provided on the inner and outer sides of the glass panel respectively.

[0022] The output terminal Y11 of the main controller U1 is connected to one end of the coil of relay KA3, and the other end of the coil of relay KA3 is connected to the neutral line N0; one end of the normally open contact KA3-1 of relay KA3 is connected to the positive voltage VCC1, and the other end is connected to one end of the external heater L3 on the panel, and the other end of the external heater L3 on the panel is connected to 0V.

[0023] Furthermore, an environmental test chamber control circuit with semiconductor refrigeration and dehumidification function also includes a relay SSRM; the output terminal Y11 of the main controller U1 is connected to one end of the relay SSRM coil, and the other end of the relay SSRM coil is connected to the neutral line N0; one end of the normally open contact SSRM-1 of the relay SSRM is connected to the live line T0, and the other end is connected to one end of the door frame heating cable L1, and the other end of the door frame heating cable L1 is connected to the neutral line N0; the door frame heating cable L1 is used to heat the door frame of the environmental test chamber.

[0024] Furthermore, the control circuit of an environmental test chamber with semiconductor refrigeration and dehumidification function also includes a relay KA4. The output terminal Y12 of the main controller U1 is connected to one end of the coil of the relay KA4, and the other end of the coil of the relay KA4 is connected to the neutral line N0. One end of the normally open contact KA4-1 of the relay KA4 is connected to the positive voltage VCC2, and the other end is connected to one end of the lighting lamp HL3. The other end of the lighting lamp HL3 is connected to 0V. The relay KA4 is used to control the on and off of the lighting lamp HL3.

[0025] In this embodiment, the positive voltages VCC1, VCC2, and VCC3 are 24V, 24V, and 12V, respectively, provided by three DC power supply modules. The main controller U1 is powered by another 24V DC power supply module.

[0026] In this embodiment, the main controller U1 is a PLC controller.

[0027] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although this utility model has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification function, characterized in that, Includes main controller U1, contactor KM1, contactor KM2, contactor KM4, relay KA1, relay KA2, relay KA5, frequency converter VFD1, phase sequence protector KVS1, and air switch CP1; One side of the three-phase normally open contact KM2-1 of contactor KM2 is connected to the three-phase live wires R0, S0, and T0, and the other side is connected to the condenser fan M1; one end of the main compressor CM1 is connected to one phase on the other side of the three-phase normally open contact KM2-1 of contactor KM2, and the other end is connected to the neutral wire N0. The input side of the frequency converter VFD1 is connected to the three-phase live wires R0, S0, and T0, and the output side is connected to one side of the three-phase normally open contact KM4-1 of the contactor KM4. The other side of the three-phase normally open contact KM4-1 of the contactor KM4 is connected to the semiconductor refrigeration fan M2. The input side of the phase sequence protector KVS1 is connected to the three-phase live wires R0, S0, and T0, and its detection terminal is connected to the live wire T0; the output terminal of the phase sequence protector KVS1 is connected to one end of the air switch CP1, and the other end of the air switch CP1 and the neutral line N0 provide AC voltage to the main controller U1. One end of the emergency stop switch SBE1 is connected to the AC voltage output from the output terminal of the phase sequence protector KVS1, and the other end is connected to one end of the start switch SB1. The other end of the start switch SB1 is connected to the AC common terminal of the main controller U1. One end of the normally open contact SUB1 for panel over-temperature detection is connected to input terminal X1 of main controller U1, and the other end is connected to the common input terminal of main controller U1; one end of the normally open contact ST2 for humidifier dry burning detection is connected to input terminal X11 of main controller U1, and the other end is connected to the common input terminal of main controller U1; one end of the normally open contact SL3 for water tank water shortage detection is connected to input terminal X12 of main controller U1, and the other end is connected to the common input terminal of main controller U1. The output terminal Y1 of the main controller U1 is connected to one end of the coil of contactor KM1, and the other end of the coil of contactor KM1 is connected to the neutral line N0; The output terminal Y2 of the main controller U1 is connected to one end of the normally open contact SL1 for water tank replenishment detection. The other end of the normally open contact SL1 for water tank replenishment detection is connected to one end of the normally open contact SL2 for water tank replenishment detection and one end of the normally open contact KA1-1 of relay KA1. The other end of the normally open contact SL2 for water tank replenishment detection and the other end of the normally open contact KA1-1 of relay KA1 are connected to one end of the coil of relay KA1. The other end of the coil of relay KA1 is connected to the neutral line N0. The normally open contacts SL1, SL2, and SL3 for water tank shortage detection are all float switches, which close when there is a water shortage and are located in the upper, middle, and lower positions of the water tank, respectively. One end of the normally open contact KA1-2 of relay KA1 is connected to the positive voltage VCC1, and the other end is connected to one end of the water supply pump M3. The other end of the water supply pump M3 is connected to 0V. The output terminal Y3 of the main controller U1 is connected to one end of the coil of contactor KM2, and the other end of the coil of contactor KM2 is connected to the neutral line N0. The output terminals Y4, Y5 and Y6 of the main controller U1 are connected to one end of solenoid valve NEU1, one end of solenoid valve NEU2 and one end of solenoid valve NEU3 respectively. The other ends of solenoid valve NEU1, solenoid valve NEU2 and solenoid valve NEU3 are connected to one end of normally open contact KM2-2 of contactor KM2. The other end of normally open contact KM2-2 of contactor KM2 is connected to neutral line N0. The output terminal Y7 of the main controller U1 is connected to one end of the coil of contactor KM4 and one end of the coil of relay KA5. The other end of the coil of contactor KM4 and the other end of the coil of relay KA5 are connected to the neutral line N0. One end of the normally open contact KA5-1 of relay KA5 is connected to the positive voltage VCC3, and the other end is connected to one end of the semiconductor refrigeration module ZL1. The other end of the semiconductor refrigeration module ZL1 is connected to 0V. The refrigeration side of the semiconductor refrigeration module ZL1 is equipped with a semiconductor refrigeration dehumidification pipeline and a semiconductor refrigeration fan M2. The output terminal Y8 of the main controller U1 is connected to one end of the solenoid valve NEU4. The other end of the solenoid valve NEU4 is connected to one end of the normally open contact KM4-2 of the contactor KM4. The other end of the normally open contact KM4-2 of the contactor KM4 is connected to the neutral line N0.

2. The control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification function as described in claim 1, characterized in that, It also includes a power indicator light HL1, one end of which is connected to the AC common terminal of the main controller U1, and the other end is connected to the neutral line N0.

3. The control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification function as described in claim 1, characterized in that, It also includes relays KA2 and KA3; The output terminal Y2 of the main controller U1 is connected to one end of the coil of relay KA2, and the other end of the coil of relay KA2 is connected to the neutral line N0; one end of the normally open contact KA2-1 of relay KA2 is connected to the positive voltage VCC1, and the other end is connected to one end of the panel heater L2, and the other end of the panel heater L2 is connected to 0V. The output terminal Y11 of the main controller U1 is connected to one end of the coil of relay KA3, and the other end of the coil of relay KA3 is connected to the neutral line N0; one end of the normally open contact KA3-1 of relay KA3 is connected to the positive voltage VCC1, and the other end is connected to one end of the external heater L3 on the panel, and the other end of the external heater L3 on the panel is connected to 0V.

4. The control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification function as described in claim 1, characterized in that, It also includes a relay SSRM; the output terminal Y11 of the main controller U1 is connected to one end of the relay SSRM coil, and the other end of the relay SSRM coil is connected to the neutral line N0; one end of the normally open contact SSRM-1 of the relay SSRM is connected to the live line T0, and the other end is connected to one end of the door frame heat tracing cable L1, and the other end of the door frame heat tracing cable L1 is connected to the neutral line N0.

5. The control circuit for an environmental test chamber with semiconductor refrigeration and dehumidification function as described in claim 1, characterized in that, It also includes relay KA4. The output terminal Y12 of the main controller U1 is connected to one end of the coil of relay KA4, and the other end of the coil of relay KA4 is connected to the neutral line N0. One end of the normally open contact KA4-1 of relay KA4 is connected to the positive voltage VCC2, and the other end is connected to one end of the lighting lamp HL3. The other end of the lighting lamp HL3 is connected to 0V.

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