Pilz PSWZ X1P static monitoring

Operation timing:

Close the safety door and the emergency stop is not activated. Press and release S3, and the feedback loop will close (due to K2 being disconnected).

When the static condition is met (the motor is not running), the "OUTPUT" LED lights up and the safety contact is closed.

Press the start button S1 and K2 to engage, and the motor will start in a star (or direct) manner.

After the motor runs, the voltage measured by PSWZ X1P is greater than Uoff, and the safety contact immediately opens (with a delay of less than 170ms), causing K2 to lose power. This action is not for power outage, but for quick disconnection in case of dangerous situations. But the external contactor control is used in this application, and the safety contacts of PSWZ X1P are only for monitoring purposes? In fact, the correct usage is that the safety contacts of PSWZ X1P should be connected in series in the self-locking path of K2 coil circuit, so that once the voltage exceeds the limit after the motor starts, the safety contacts will disconnect and K2 will be immediately released. This provides an anti accidental restart function.

When stopping normally, press the stop button, release K2, and the motor will run with inertia.

When the speed drops to zero, the residual magnetic voltage is lower than Uon, and both channels meet the conditions within 7 seconds, the PSWZ X1P closes the safety contacts again, allowing the next start.

Attention: During the star delta switching process, the measurement line must be connected to the motor terminal, not the contactor input terminal, otherwise the measurement signal will be lost at the moment of switching.

Troubleshooting and Common Problems

The PSWZ X1P provides status and fault indication through the front LED. The following are typical fault phenomena and their solutions.

Possible causes and solutions for LED status

POWER does not light up and there is no power supply/wrong power connection/fuse burnt out/internal damage. Check the voltage of A1 and A2 and the external fuse. Confirm that the voltage is within the rated range (24-240V AC/DC).

POWER is on, but CH.1 IN and CH.2 IN are not on, and the motor has come to a standstill. The response threshold is set too low (too much counterclockwise) or the measurement circuit is open. Adjust the potentiometer clockwise until the LED lights up. Check if the wiring of L1, L2, and L3 is broken or has poor contact.

In CH.1 IN/CH.2 IN, only one bright single channel voltage is below the threshold, while the other channel is above the threshold (possibly due to motor rotation causing phase voltage imbalance). Check if the motor wiring is missing phase. Measure the voltage of L1-L3 and L2-L3 in millivolt range using a multimeter (when the motor is stationary). If the difference is too large, it may be due to asymmetric residual magnetism of the motor, and it is necessary to reduce sensitivity or contact the manufacturer.

**OUTPUT is not lit, but both input LEDs are lit * * Feedback loop Y1-Y2 is not closed. Check if the external contactor normally closed auxiliary contact is connected. Temporary short circuit Y1-Y2 test (for diagnostic purposes only, cannot be permanently short circuited).

Press the reset button (to give RESET a high-low pulse) when the FAILT LED lights up at the same time or when the single channel voltage drops beyond the tolerance. If it repeatedly occurs, check whether the motor has completely stopped within 7 seconds (such as due to excessive inertia) or if there is poor contact in the measurement circuit.

The safety contact cannot be closed, even if the OUTPUT lights up and the relay contact is mechanically faulty or the welding power is cut off, manually test the contact resistance. If it doesn't work, replace the device.

During motor operation, if the safety contacts are not disconnected and the measured voltage does not reach Uoff (possibly due to low motor voltage), check if the rated voltage of the motor matches the actual power supply. The minimum measured voltage for PSWZ X1P is 0V, but the voltage must be greater than 2 × Uon during startup. If the motor is small, the residual voltage may always be lower than Uoff, causing the safety contacts to fail to operate. Solution: Choose a low threshold model.

Weekly mandatory testing (compliant with safety standards):

According to the manual, the following tests must be performed at least once a week:

Start the motor and confirm that all LEDs (except POWER) are turned off and the safety contacts are disconnected (measured with a multimeter 13-14).

Stop the motor.

Observe whether the CH.1 IN, CH.2 IN, and OUTPUT lights up again after the motor shaft is completely stationary. If it is not restored, it indicates that the static threshold is set improperly or there is abnormal residual magnetism in the motor.

Common Misunderstandings Clarification:

Misconception 1: PSWZ X1P can be used for speed monitoring. In fact, it can only distinguish between "rotation" and "stillness" and cannot measure specific rotational speeds.

Misconception 2: The output end of the frequency converter can be directly measured. Sure, but it is necessary to ensure that the inverter completely shuts off the output (i.e. the inverter pulse is blocked), otherwise high-frequency interference and high voltage may occur, which may damage the measurement circuit.