1. Common faults of power regulators
1. The load has no output, or the load voltage cannot be increased
1) Check the power supply: whether the control board and load power supply are normal, and whether the fast fuse is burned out.
2) Check the load: whether the load is open circuit or there is a problem with the wiring.
3) Check the status light of the control panel: green, running status; yellow flashing, shutdown status (no output); red, overcurrent alarm (no output); red flashing, power supply phase loss (no output) ; Flashing red and green, radiator over-temperature alarm (no output); solid yellow, control board failure; not lit, no power supply or control board failure.
4) Check the input indicator light on the control panel: green, the brightness should change with the input signal.
5) Check the position of the p1 potentiometer on the control board: adjust clockwise to increase the output voltage.
6) Check the R1 and R2 short-circuit pieces on the control board: During automatic control, the R1 and R2 short-circuit pieces should be connected properly.
7) Check the input signal: range, 4~20mA. Input signal 》5.6mA, there should be output. Whether the polarity is reversed.
8) Check the R2 end of the control board: R2 outputs 0~5V (varies with the input signal 4~20mA).
9) Check the RS terminal of the control board: the RS and GND terminals are short-circuited, in shutdown state (no output), and the status light flashes yellow.
10) Check the current limit potentiometer: whether the current limit value is adjusted too low.
2. The load voltage is abnormal
1) Check the power supply: whether the control board and load power supply are normal. The control board power supply should be in the same phase as the load power supply.
2) Check the load: whether it is running at no load or light load. Transformer load: The secondary side cannot be unloaded and must be fully loaded.
3) Manual inspection: If the manual control is normal, it is initially judged that there is no problem with the voltage regulator. Otherwise, connect the dummy load and continue checking.
4) Automatic check: When the control input changes by 4~20mA, the voltage change range of R2 terminal should be 0~5V.
5) The output voltage can only be adjusted to half of the load power supply: one arm of the thyristor module of the voltage regulator is damaged.
6) Check whether the RC absorber is in poor contact or damaged.
3. The load voltage is always larger and uncontrolled, the output is always larger, and it cannot be adjusted either manually or automatically.
Possible reasons:
1) The load may be open circuit or the load is not connected.
2) The thyristor module of the voltage regulator is damaged due to breakdown. The resistance at the output end of the thyristor module is generally greater than 500KΩ.
4. It starts running normally. After a period of time, the output is always larger. Neither manual nor automatic is adjustable. After shutting down and then restarting, it cannormal operation.
Possible reasons:
1) The ambient temperature is too high.
2) The load is overcurrent for a long time.
3) The instantaneous overcurrent of the load causes thermal breakdown of the thyristor module.
5. Connect a dummy load and debug according to the simplest wiring. If the fault location is difficult to determine, the dummy load debugging method can be used. The dummy load is generally a 100~200W light bulb.
1) Manual adjustment is normal: It is initially judged that the voltage regulator is normal, and it is suspected that there is a problem with the load. It is necessary to check the load power supply voltage, fuse and poor contact, disconnection, short circuit, insulation degradation, discharge and sparking, etc.
2) Manual adjustment is normal, automatic adjustment is abnormal: If the control input 4~20mA current is abnormal, the instrument needs to be further checked; otherwise, it is necessary to check whether the p1 potentiometer has adjusted the voltage limiter too low, R1 , R2 short-circuit piece is connected properly.
3) Both manual and automatic adjustments are normal: it is judged that there is no problem with the voltage regulator.
2. Common faults of SCR power regulator
1. The maximum current of the electric heater gradually decreases during operation
Cause analysis: The internal electric heating tube is burned. The electric heater is installed horizontally. During operation, the gas medium contains a lot of dust or the air pressure difference between the inlet and outlet of the electric heater is low, causing dust to deposit inside the electric heater and cover the electric heating tube, causing the heat of the electric heating tube to not be dissipated. Eventually the electric heating tube will burn out, and the bottom electric heating tube is most likely to burn out.
Troubleshooting: Regularly record the operating current of each group of electric heaters. When it is found that the maximum operating current of an individual group of electric heaters gradually decreases, it can be determined that the internal electric heating tube is burned out. The burning of a small number of electric heating tubes will not affect When the system is running, the electric heating tube can be replaced while the unit is shut down for maintenance. If most of the electric heating tubes are burned out and the heater outlet temperature cannot meet the needs of the system, the maximum power of the electric heating of the failed group can be appropriately increased to ensure normal operation of the system.
2. The operating temperature of a certain group of SCR power regulator thyristors is >60°C, causing contactor interlock tripping
Cause analysis: SCR power regulator The heat dissipation fan of the heater does not rotate, and the heat dissipation efficiency of the heater cabinet is low.
Troubleshooting: Open the front door of the heater control cabinet immediately to let the air conditioning air in. If the cooling fan does not turn, contact maintenanceTeams are replaced.
3. The measured temperature at the outlet of the electric heater is greater than the set value for a long time
Cause analysis: the control method is incorrect, and the air volume and air pressure inside the heater body are low , thermostat and control circuit failure.
Troubleshooting: Check whether the remote manual or automatic control parameters are correct, increase the air volume of the main body, and increase the air pressure. Check and repair thermostat. Tighten the connecting wires of each terminal block.
4. The actual measured temperature of a certain group of electric heaters is equal to or greater than the set value
Cause analysis: the air volume inside the body is low, dust accumulation is serious, and the temperature measurement If the temperature is not correct, the thermostat is damaged.
Troubleshooting: Immediately stop the operation of a certain group of heaters to prevent the electric heating tube from burning and increase the air volume inside the body. Check and calibrate the thermostat and temperature measuring points.
5. A certain group of electric heaters tripped individually
Cause analysis: over-temperature inside the body, over-temperature of the thyristor, control component and circuit failure.
Troubleshooting: Single-group heater protection interlock trip conditions include over-temperature inside the body, over-temperature of the thyristor, control component and circuit failure. When a certain group of heaters trips, the fault point should be quickly found, confirmed, and eliminated, otherwise the normal operation of the unit will be affected. In the design of the electrical control circuit, each tripping condition corresponds to an intermediate relay, and the tripping condition can be determined through the indicator light of the intermediate relay. When the indicator light of the intermediate relay lights up, it means that the corresponding tripping condition has been triggered. When an over-temperature fault occurs inside the body, you should immediately check and verify whether the temperature measuring points and the thermostat are working properly. At the same time, increase the air pressure and flow rate, and wait until the temperature drops to the interlock trip value before it can be put into operation. When a thyristor over-temperature failure occurs, the SCR power regulator cooling fan should be checked and replaced. Failures of control components and circuits are mostly caused by loose fuses, intermediate relays, and connecting wires. Replace damaged fuses, intermediate relays, and tighten the connecting wires of the circuit.
6. Four sets of electric heaters tripped at the same time
Cause analysis: operator misoperation and improper adjustment of equipment parameters, heater outlet overtemperature, system connection Lock protects against tripping, control component and circuit failures.
Troubleshooting: Operators should control the equipment correctly according to the working conditions of the unit, check and restore the interlocking parameters of the equipment to not exceed the set values, and check and verify the heater outlet temperature measuring point and thermostat. , check and replace the intermediate relay.
3. Precautions when using the power regulator
When the SCR power regulator is used, heat will be generated internally. Please install it vertically with both sides required. Leave a gap to avoid SCR damage caused by poor heat dissipation. The control box must have air convection vents. Please install vents or install an exhaust fan according to the principle of hot air flowing from bottom to top.
Avoid installing in places with severe water vapor or acid, alkali, corrosiveGas place. Do not install in places with high temperatures or poor ventilation. Ambient temperature -10℃-45℃; ambient humidity: below 90%RH (no condensation).
When the SCR has not been used on the machine for three months, please remove the dust on the surface before running the machine. Regular maintenance is required as dust, oil and many other phenomena may cause short circuits.
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