Secondary wiring errors in the power distribution cabinet may affect the normal operation of the equipment and even cause safety accidents. The following are some common secondary wiring errors and corresponding solutions:
Types and phenomena of wiring errors
Short circuit
Phenomenon: The fuse melts at the moment of closing the switch, or the air switch trips; the relevant protection device is activated and an alarm signal is issued; it may be accompanied by obvious fault phenomena such as sparks and smoke.
Cause: The insulation layer of the wire is damaged, so that the wires of different phases are in direct contact; the terminals of different potentials are mistakenly connected together during wiring; during the wiring process, the wires squeeze each other, causing damage to the insulation layer.
Solution: Use an insulation resistance meter to detect the short-circuit point, measure the insulation resistance of each circuit in sections, and gradually narrow the scope of the fault; carefully check the insulation of the wire, find the damaged part, wrap it with insulating tape or replace the wire; recheck the wiring to ensure that the terminals of different potentials are correctly connected.
Open circuit
Phenomenon: The relevant control circuit cannot work normally, such as the relay does not work, the indicator light is not on, the instrument has no display, etc.; there is no abnormal current or voltage in the measurement circuit.
Cause: The wire connection is loose, such as the terminal screws are not tightened; the wire is broken in the middle, which may be due to excessive bending or external force during installation; the fuse is blown, causing the circuit to be disconnected.
Solution: Use a multimeter to check the on-off status of each connection point, tighten the loose terminal; find the broken wire, reconnect or replace the wire; check the fuse, if it is blown, replace the fuse of the same specification.
Wrong wiring
Phenomenon: Abnormal operation of the equipment, such as wrong motor direction, malfunction of the protection device, etc.; the control logic is chaotic and the expected control function cannot be achieved.
Cause: Wiring is not performed according to the wiring diagram, the terminal number or line direction is misread; there are errors or unclear markings in the drawing itself.
Solution: Check the connection of each wire against the correct wiring diagram and correct the wrong wiring; if the drawing is suspected to be wrong, communicate with the designer in time to confirm the correct wiring method.
Poor insulation
Phenomenon: The insulation resistance value is lower than the specified standard, which may cause leakage, and in severe cases, it may cause electric shock accidents; grounding faults may occur, causing the protection device to operate.
Cause: The wire is damp, such as the distribution cabinet is not sealed tightly, and water vapor enters; the insulation material is aged and damaged, which reduces the insulation performance; the environment is humid or there are corrosive substances, which damages the insulation layer.
Solution: Dry the damp wires, which can be heated and ventilated; replace aging and damaged insulation materials, such as insulating tape, insulating sleeves, etc.; improve the operating environment of the distribution cabinet, strengthen the seal, and take moisture-proof and anti-corrosion measures.
Preventive measures
Strictly follow the design drawings and construction specifications for wiring. Before wiring, carefully check the models and specifications of the drawings and components.
Strengthen the training of construction personnel, improve their wiring skills and quality awareness, and avoid wiring errors due to improper operation.
Regularly maintain and overhaul the distribution cabinet to promptly detect and deal with problems such as loose wiring and aging insulation.
After the wiring is completed, a comprehensive inspection and test should be carried out to ensure that the wiring is correct and the insulation is good.
