Air Preheater Shutdown Analysis
First, the cause of the malfunction
1. Disintegration examination found that the contactor within the same slot main contacts (B phase) and auxiliary contacts (A phase) caused ashort circuit in the power transmission, then the contact burned. Analysis:during the thermocouple movement of the speed reducer pump, the contactor has been internal Overheating and burning, causing short circuit when power transmission.
2. Air preheater reducer pump wiring for screw compression thread, easy to get rid of by external forces, resulting in lack of phase motor operation.
3. The operator only shakes the motor insulation when sending power, but not shaking the contactor insulation (contactor air switch).
4. Original design problems, air preheater have the 2-way power supply, respectively, during normal operation with an air preheater and ancillary equipment operation, 2-way power supply each other standby, and interoperability, so that when one way of the power supply accoured a permanent malfunction, the other way of power supply will put itself to the point of malfuction, resulting in two power loss, and air preheater are stopped, a direct threat to the normal operation of the unit.
Second, the measures should adopt
1. The same slot main contacts and auxiliary contacts connected to the same group.
2. Fixed the air preheater motor cable from the junction box at 10 cm , other motors are also similar to the same reinforcement.
3. For contactor and air switch wiring, when test insulation after the stopped malfunction, at the same time test the contactor upper and lower insulation, all are qualified to send electricity
4. Operation mode Uehara 2-channel power supply with an air preheater, 2-way power supply for each other's dark standby, should be replaced by a clear standby or cancel the automatic interconnection (in a case of air preheater failure, to identify the situation after the manual power transmission) .
5.On the gate equipment, maintainer should check the switch and contactor at the same time whether there is any loss after the case.By taking measures to revamp the air preheater circuit and to operate the overhaul, a similar situation has not occurred in the air preheater, thus effectively preventing the downtime caused thereby.