Overview
The temperature and humidity controller is based on an advanced single-chip microcomputer as the control core, and adopts imported high-performance temperature and humidity sensors, which can measure and control temperature and humidity signals at the same time, and realize liquid crystal digital display. The lower limit is set and displayed, so that the instrument can automatically start the fan or heater according to the on-site situation, and automatically adjust the actual temperature and humidity of the measured environment.
Working principle
The temperature and humidity controller is mainly composed of three parts: sensor, controller and heater. Its working principle is as follows: the sensor detects the temperature and humidity information in the box, and transmits it to the controller for analysis and processing: when the temperature and humidity in the box reach or When the preset value is exceeded, the relay contact in the controller is closed, the heater is powered on and starts to work, heating or blowing air in the box; after a period of time, the temperature or humidity in the box is far from the set value, and the The relay contacts in the appliance open, heating or blowing stops.
Application
Temperature and humidity controller products are mainly used for the adjustment and control of the internal temperature and humidity of medium and high voltage switch cabinets, terminal boxes, ring network cabinets, box transformers and other equipment. It can effectively prevent equipment failures caused by low temperature and high temperature, as well as creepage and flashover accidents caused by moisture or condensation.
Classification
Temperature and humidity controllers are mainly divided into two types: ordinary series and intelligent series.
Ordinary temperature and humidity controller: It is made of imported polymer temperature and humidity sensor, combined with stable analog circuit and switching power supply technology.
Intelligent temperature and humidity controller: It displays temperature and humidity values in the form of digital tubes, and has heater, sensor fault indication, and transmission functions. The instrument integrates measurement, display, control and communication. It has high precision and wide measurement range. A temperature and humidity measurement and control instrument suitable for various industries and fields.
Selection guide
The intelligent temperature and humidity controller can measure at multiple points at the same time, and control the temperature and humidity of the environment at multiple points. The following information should be included when ordering: product model, auxiliary power supply, controller parameters, cable length, heater.
Maintenance
Maintenance of temperature and humidity controller:
1. Always check the working condition of the controller.
2. Check whether the working condition of the refrigerator is normal (if there is less fluoride, fluoride should be replenished in time).
3. Check whether the tap water supply is sufficient. If there is no water, turn off the humidification switch in time to avoid burning out the humidifier.
4. Check the cables and heaters for leakage.
5. Check whether the spray head is blocked.
6. Note that the humidification water pump will stop rotating due to the water sediments that are not used for a long time, and turn the fan blade at the toggle port to make it rotate.
Matters needing attention
1. The monthly “daily inspection” should check the integrity of the temperature and humidity controller, and report the problem in time to keep it in good condition. The distance between the heating pipe and the cable and wire is not less than 2cm;
2. The temperature and humidity controllers of all terminal boxes and mechanism boxes should be placed in the input position, so that the temperature and humidity are controlled within the standard range.
3. Since the digital display temperature and humidity controller does not have a memory function, every time the power is turned off, the factory settings will be restored after the power is turned on again, and the settings should be reset.
4. Avoid using the temperature and humidity controller in an environment with high dust concentration. Try to install the machine in an open place. If the room measured by the machine is large, increase the number of temperature and humidity sensors.
Troubleshooting
Common faults of intelligent temperature controllers:
1. After heating for a period of time, the temperature does not change. Always display the on-site ambient temperature (such as room temperature 25°C)
When encountering such a fault, first check whether the SV value setting value is set, whether the OUT indicator light of the meter is on, and use a “multimeter” to measure whether the 3rd and 4th terminals of the meter have 12VDC output. If the light is on, terminals 3 and 4 also have 12VDC output. It means that the problem lies in the control device of the heating body (such as AC contactor, solid state relay, relay, etc.), check whether the control device has an open circuit and whether the device specification is wrong (such as a 380V device in a 220 circuit), Whether the line is connected incorrectly, etc. In addition, check whether the sensor is short-circuited (when the thermocouple is short-circuited, the meter always displays room temperature).
2. After heating for a period of time, the temperature display is getting lower and lower
When encountering such a fault, the positive and negative polarities of the sensor are generally reversed. At this time, you should check the input terminal wiring of the instrument sensor (thermocouple: 8 is connected to the positive pole, and 9 is connected to the negative pole; PT100 thermal resistance: ?8 is connected to the single-color wire, 9 and 10 are connected to two wires of the same color).
3. After heating for a period of time, the temperature value (PV value) measured and displayed by the meter is very different from the actual temperature of the heating element (for example, the actual temperature of the heating element is 200°C, while the meter displays 230°C or 180°C)
When encountering such a fault, first check whether the contact point between the temperature probe and the heating body is loose and other poor contact, whether the selection of the temperature measuring point is correct, and whether the specification of the temperature sensor is consistent with the input specification of the temperature controller (such as the temperature control meter). It is a K-type thermocouple input, and a J-type thermocouple is installed on site to measure the temperature).
4. The PV window of the instrument displays HHH or LLL characters.
When such a fault is encountered, it means that the signal measured by the instrument is abnormal (LLL is displayed when the temperature measured by the instrument is lower than -19°C, and HHH is displayed when the temperature is higher than 849°C).
Solution: If the temperature sensor is a thermocouple, you can remove the sensor and directly short-circuit the thermocouple input terminals (terminals 8 and 9) of the instrument with wires. ℃), the problem lies in the temperature sensor, use a multimeter tool to detect whether the temperature sensor (thermocouple or PT100 thermal resistance) has an open circuit (broken wire), whether the sensor wire is connected reversely or wrongly, or the sensor specifications are inconsistent with the instrument.
If the above problems are eliminated, the internal temperature measurement circuit of the instrument may be burned due to the leakage of the sensor.
5. The control is out of control, the temperature exceeds the set value, and the temperature has been rising.
When encountering such a fault, first check whether the OUT indicator light of the meter is on at this time, and use the DC voltage range of the “multimeter” to measure whether the 3rd and 4th terminals of the meter have 12VDC output. If the light is off, terminals 3 and 4 do not have 12VDC output either. It indicates that the problem lies in the control device of the heating element (such as; AC contactor, solid state relay, relay, etc.).
Solution: Check the control device immediately for short-circuit, unbreakable contact, wrong circuit connection, etc.
Post time: Nov-26-2022