（一） Abnormal sound of the transformer
The first step is to distinguish between electromagnetic and mechanical sounds. The general situation is:
1. The screw of the transformer core clamping piece is loose
The sharp Angle of the iron core shall be knocked out of shape when the user transports and installs it, or there may be foreign matter overlapped in the iron core.
Produce mechanical sound: The fan fixed screw is loose, there is debris in the interior. Loose fixing screws in the housing cause noise of panel vibration. The transformer's low-voltage busbar fixing screws are loose, or the busbar is not soft-connected, so the vibration produces noise.
2. the input power voltage is too high, over-excitation, loud
3. The sound produced by high harmonics. It is characterized by irregularity. It's loud, it's loud, it's quiet, it's quiet. Mainly is the power side or the load has the electric furnace, the silicon controlled rectifier equipment produces the high order harmonic feedback to the transformer.
4. Environmental issues. Mainly is the transformer room around the small space, smooth wall, easy to produce sound box effect, so that the transformer sound bigger.
（二）The thermometer shows abnormally
As the sensor of the thermometer USES platinum resistance and is made of very thin metal wire, abnormal thermometer readings may occur. Common frequently asked questions are:
a.The sensor is not plugged into the socket behind the temperature display, the fault light is on, the screen shows OP,
b.The sensor connector is loose, the resistance increases, and the temperature value shows high.
c.The temperature of a certain phase is infinite and the platinum resistance wire of the sensor is open
d.The platinum resistance of the sensor is in the state of breaking or not breaking when the temperature of a certain phase is high.
4. Creepage is found on the coil surface of transformer. This situation is generally caused by air moisture, surface dust, water leakage. There are also foreign matter (secondary leads, thermostat sensor leads, etc.) close to coils that produce discharges. For the metal surface discharge, such as clamp, is generally the discharge of the suspended potential of the loose fastener.
Varelen Electric Co., Ltd