06/20/2020
What are the causes of air conditioning trip
What are the causes of air conditioning trip
1. The contradiction between the rated current of the air conditioner and the current carrying capacity of the wire.
Here are two formulas involved:
①The rated current of air conditioner I=P÷U ÷power factor, the power remains unchanged, the smaller the voltage, the greater the current required.
② The current carrying capacity of the wire I=U÷R, the voltage is proportional to the current.
So when the power supply voltage is normal, we must consider the line voltage drop. The longer the line, the greater the resistance, the greater the voltage drop, and the smaller the output current at the end. However, because the power of the load remains unchanged, the voltage becomes smaller, and the current that needs to be output will be larger. At this time, the wire is forced to overload, and the time will cause heating, and eventually cause the tripping of the open circuit.
Some friends said that the heat of the wire will not cause the tripping of the circuit breaker. In fact, the manufacturer of the air switch has made it clear in the relevant manuals that the heat of the wire will cause the air switch to trip. Because the wire heats up, the crimp terminal will also heat up, and the resistance will become larger and larger. The larger the resistance, the greater the current consumption, and the hotter it will be, a vicious cycle.
2. Leakage
During the daily maintenance work, we will encounter the situation that the air circuit trips due to the leakage of electricity. At least I have not experienced it once or twice. Regardless of the leakage of the neutral line or the leakage of the live line, a long time will cause the circuit breaker to trip.
Why does the electric leakage cause the MCB to trip? There are two situations.
① Good grounding. At the beginning, the leakage current was not large, and as time went by, the leakage current became larger and larger, and eventually evolved into a short circuit to ground, unable to close.
②There is no ground wire. If the equipment is not connected to the protective ground, when the wire leaks to the equipment, it is equivalent to adding a large shunt resistance. Like this problem, if the air conditioner does not have a ground wire, when the wire leaks to the air conditioner, the air conditioner is a very large shunt resistor and will consume a lot of current. Eventually, the wire will heat up or trip open.
How to determine whether the trip caused by the above two aspects can be done with a clamp ammeter.
① Measure the voltage at the input and output to see if there is a significant change in voltage drop.
②Measure whether the output current exceeds the standard.
So my suggestion is: first measure the supply voltage to see if it is within the allowable fluctuation range. Then measure the current to see if it exceeds the rated ampacity of the wire. Finally, check the data one by one according to the measured data to find out the reason.
