YORK YK — Warning - Surge protection - Excess surge limit

The panel shows Warning - Surge protection - Excess surge limit. While the extended run period is active, the control center also displays the time remaining in the 10 min period. The warning stays on for the whole period, during which the PRVs are driven closed.

This warning announces that the chiller has entered the surge protection extended run period. It appears only when the surge protection extended run feature is enabled. The period begins because the surge window count has gone above the count limit. For the next 10 min the chiller runs with the PRVs driven closed, and a load inhibit on the PRVs is in effect for as long as the message is displayed.

• The trigger is a surge window count that exceeds the count limit; the warning applies only while the surge protection extended run feature is enabled and one of the following conditions is present:
• Hot gas is disabled on an SSS or EM starter application.
• Hot gas is enabled and the HGBP valve command reaches 100% on an SSS or EM starter application.
• Hot gas is disabled on a VSD application while the VSD command frequency is at maximum frequency.
• Hot gas is enabled on a VSD application with the HGBP valve command at 100% and the VSD command frequency at maximum frequency.

• Surge protection extended run — this feature must be enabled. With it enabled and the shutdown setpoint disabled, the control drives the PRVs closed for 10 min and displays this warning.
• Count limit — the extended run period starts when the surge window count goes above this limit, and the warning clears after 10 min only if the count is then at or below the limit.
• Shutdown setpoint — if this is enabled and the surge window count still exceeds the count limit at the end of the 10 min period, the control performs a safety shutdown.

The message and the PRV load inhibit clear on their own: When 10 min have elapsed, this message and the PRVs load inhibit are automatically cleared. The automatic clearing happens only if the surge window count is then less than or equal to the count limit. The message and the load inhibit are also cleared when the chiller is shutdown. If the shutdown setpoint is enabled and the surge window count still exceeds the count limit when the 10 min period ends, the control performs a safety shutdown instead.