Steps for debugging a dual-power automatic transfer switch

Place the automatic transfer switch onto the test bench. Connect the corresponding power cables in the correct phase sequence. Match phase wires and neutral wires to designated terminals; incorrect wiring is prohibited.

For commissioning of 3-pole switches, the neutral wire of the normal supply and the neutral wire of the standby supply shall be connected to neutral terminals NN and RN respectively.

Switch on the normal power supply and standby power supply, then press the start button.

Set the automatic transfer switch to automatic transfer and reclose mode. If voltages of both power supplies are normal, the switch shall switch to the normal supply position and close the normal supply contact.

Simulate phase loss of any phase (NA, NB, NC, NN) on the normal supply. The ATS shall automatically transfer to the standby supply. When the normal supply recovers, the switch shall transfer back to the normal supply.

Adjust the voltage of any phase of the normal supply down to the preset undervoltage threshold. The ATS shall automatically switch to the standby supply. When the normal supply voltage returns to normal, the switch shall revert to the normal supply side.

If any phase of the standby supply suffers phase loss, the alarm shall sound.

Disconnect any phase of the normal supply or standby supply. The corresponding indicator symbol on the controller shall disappear accordingly.

When the ATS is set to manual mode, operate the controller manually to switch freely between standby supply and normal supply. The display shall show correct status in both positions.

Press the dual open button on the controller. The ATS shall disconnect both the normal supply and standby supply simultaneously and stay at the dual-open position.

While the switch is closed, set the multimeter to the AC 750 V range. Compare readings with the voltmeter on the test bench and check signal output terminals. Verify that power indication, closing indication and voltage at the outgoing terminals of the circuit breaker are normal.

If the switch is equipped with generator control function: set the multimeter to buzzer mode and measure the generator signal terminal. The buzzer shall remain silent when the normal supply is available. When Phase A of the normal supply fails or the normal supply is fully cut off, the buzzer shall emit continuous beeps. If no beep occurs under normal supply outage, the generator signal circuit is faulty.

If the switch supports fire control function: apply DC 24 V to the fire control terminals, matching positive and negative poles correctly. Upon power application, the ATS shall automatically open and move to the dual-open position.

For manual mechanical switching: first press the dual open button on the controller to set the ATS to dual-open position. Then rotate the switch using the dedicated handle according to position indicators. Do not apply excessive force or rotate in the wrong direction.

Upon completion of ATS commissioning: turn off the power supply or press the stop button to confirm power cut-off, then disconnect all power cables.