If the temperature in the monitored area exceeds the normal reaction temperature of each PTC sensor, the resistance of the sensor will increase, and the INT69 motor protector will close the motor current contactor.
When the temperature drops to about 3K below the specified temperature, the module is restarted. The output relay provides voltage-free convertible connection, and at the same time, as long as the temperature does not exceed the normal temperature, it will provide energy, making it have the function of self-monitoring. Because this device also acts on PTC, or causes an open circuit.
Extended data:
Combustion cause
In practical application, there are many reasons for motor burning, which can be roughly divided into the following categories:
(1) Motor overload and excessive current caused by various reasons;
(2) Current imbalance, phase imbalance or phase loss caused by too low or too high voltage (including phase loss caused by contactor failure);
(3) The return air pressure caused by refrigerant leakage or pipeline problems is too low, and the motor is insufficiently cooled;
(4) The winding insulation layer is damaged or the water content of the refrigerant is too high, resulting in short circuit burning.
Theoretically, the overload protector can effectively deal with the first two situations, and the thermal protector can deal with the first three situations.
The "short circuit" in the fourth case may be related to quality or installation, or it may be related to the high water content of metal chips or refrigerants. In actual use, several situations may occur at the same time, which are mutually causal. It is impossible to always test with a brand-new compressor like a laboratory, and the problem is often simplified. ?
The biggest limitation of the thermal protector and overload protector used at present is that they can't avoid all the above phenomena from the root, so the protection of the motor can only stay in the "cooling therapy" afterwards, that is, temporarily stop the machine, let the compressor cool naturally, and then run.
There is no limit to the number of times the thermal protector and overload protector are pulled in, and the motor will often burn out in the cycle of "protection-operation-re-protection-re-operation". For emergencies, such as winding insulation damage or short circuit caused by copper sheets, the motor will burn out at high temperature in an instant, and the thermal protector and overload protector will not be able to respond and cannot be protected.
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