YORK YMC2 — SAFETY STOP

The OptiView control center shows SAFETY STOP. This message is set when the hardware safety stop pushbutton, located on the side of the control panel, is depressed. While the button stays depressed, the chiller does not run under any condition, so the message remains until the button is released and the fault is cleared.

SAFETY STOP indicates that the panel safety stop hardware pushbutton is depressed. Pressing the button removes the input from the I/O Board terminal TB3-28, and once this input has been removed for more than 500 msec continuous, the message is set; at the same time the local command is set to STOP. The safety stop exists for safety reasons, and this position is required for many maintenance tasks to be completed. It is not intended for normal shutdown of the chiller: if it is used, an immediate stop occurs which bypasses the programmed controlled shutdown. If the switch is pressed while a soft shutdown is in progress, the soft shutdown is terminated immediately and a system coastdown takes place instead, during which the run signal is removed from the VSD.

• The panel safety stop hardware pushbutton on the side of the control panel has been depressed — for example because a maintenance task requires this position, or in an unusual circumstance requiring immediate stoppage.

1. Confirm that the message comes from the hardware safety stop button on the side of the control panel and establish why it was pressed — a maintenance task or an unusual circumstance requiring immediate stoppage.
2. Make sure the reason for the stop has passed and that it is safe to release the stop condition.
3. Rotate the safety stop button clockwise to release the stop condition.
4. Press the CLEAR FAULTS button on the OptiView panel.
5. Restart the chiller. For regular operation use the normal stop, not the safety stop: the normal stop eases the driveline to stop, while the safety stop produces an immediate stop.

• The message is set when input from the I/O Board terminal TB3-28 is removed for more than 500 msec continuous.
• Setting the message also sets the local command to STOP.

The stop condition is released by rotating the safety stop button clockwise. Then clear the fault from the panel: The chiller can be started when the pushbutton is released and the OptiView panel CLEAR FAULTS button is pressed. While the button remains depressed, the chiller will not run under any condition.