What are the common faults of SCR power regulators?
1. The maximum current gradually decreases during the operation of the electric heater Cause analysis: The internal electric heating tube is burned. The electric heater is installed horizontally, there is more dust in the gas medium during operation, or the pressure difference between the inlet and outlet of the electric heater is low, which causes dust to deposit inside the electric heater and cover the electric heating tube, resulting in the heat of the electric heating tube cannot be dissipated Finally, the electric heating tube is blown out, and the bottom electric heating tube is the easiest to blow.
Troubleshooting: Regularly record the operating current of each group of electric heaters. When it is found that the maximum current of individual groups of electric heaters gradually decreases, it can be determined that the internal electric heating tube is burned out. A small number of electric heating tube burnouts will not affect the system operation. Replace electric heating tube during shutdown inspection. If most of the electric heating tubes are blown and the heater outlet temperature cannot meet the system requirements, the maximum power of the electric heating of the faulty group can be appropriately increased to ensure the normal operation of the system.
2. A certain group of SCR power regulator SCR working temperature> 60 ℃, causing the contactor to trip interlock Reason analysis: The cooling fan of the SCR power regulator does not rotate, and the heat dissipation efficiency of the heater cabinet is low.
Troubleshooting: Immediately open the front door of the heater control cabinet and let the air conditioner cool air in. If the cooling fan does not turn, contact the maintenance team to replace it.
3. The measured temperature at the outlet of the electric heater is greater than the set value for a long time Reason analysis: The control mode is wrong, the air volume and pressure inside the heater body are low, and the thermostat and control circuit are faulty.
Troubleshooting: Check whether the remote manual or automatic control parameters are correct, increase the body air volume, and increase the air pressure. Check and repair the thermostat. Tighten the connecting wires of each terminal block.
4. The measured temperature of a group of electric heaters is equal to or greater than the set value Cause analysis: The air volume inside the body is low, the dust accumulation is serious, the temperature measurement point is not accurate, and the thermostat is damaged.
Troubleshooting: Immediately stop the operation of a group of heaters to prevent burning of the electric heating tube and increase the internal air volume. Check and verify the thermostat and temperature measuring point.
5. A group of electric heaters single trip Cause analysis: overtemperature inside the body, thyristor overtemperature, control element and loop failure.
Troubleshooting: The single-group heater protection interlock trip conditions include overtemperature inside the body, thyristor overtemperature, control element and circuit failure. When a group of heaters trips, it should quickly find and confirm and eliminate the fault point, otherwise it will affect the normal operation of the unit. In the design of the electrical control loop, each trip condition corresponds to an intermediate relay. The trip condition can be determined by the intermediate relay indicator. When the intermediate interrupter indicator lights up, it indicates that the corresponding trip condition has been triggered. When an over-temperature fault inside the main body occurs, you should immediately check and verify whether the temperature measurement point and the thermostat are working properly. At the same time, increase the air pressure flow and wait for the temperature to reach the interlock trip value before it can be put into operation. When a SCR over-temperature fault occurs, the cooling fan of the SCR power regulator should be checked and replaced. Control element and circuit failures are mostly caused by the loosening of the fuse, intermediate relay and connecting wire. Replace the damaged fuse and intermediate relay and tighten the connecting wires of the circuit.
6. Four sets of electric heaters trip simultaneously
Reason analysis: the operator misuses the equipment parameter adjustment improperly, the heater outlet over temperature, the system interlock protection trips, the control element and the circuit breakdown
Troubleshooting: The operating personnel should correctly control the equipment according to the working conditions of the unit, check and restore each interlocking parameter of the equipment to not exceed the set value, check and verify the temperature measurement point of the heater outlet and the thermostat, and check and replace the intermediate relay.
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