Johnson Controls YORK YVAM 0350, Operation & Maintenance Manual

Page: 21 / 162

Surge protection
The surge protection feature detects surge events. It provides a running count of the surges
detected over the lifetime of the chiller. It allows the user to define how many surges are excessive
and how the control reacts to an excess surge condition. When excessive surging is detected, this
feature can shut down the chiller.
Surge events are detected by monitoring the relationship between the condenser pressure
and evaporator pressure while the chiller is running. An excess surge condition is detected by
comparing the number of surge events that occur in a selectable time period to a selectable
threshold.
If the number of surge events (Surge Window Count) detected in the time period programmed
as the Count Window setpoint (1 minute to 5 minutes, default 5 minutes) exceed the threshold
programmed as the Count Limit setpoint (4 to 20, default 4), an excess surge condition has been
detected.
Unless the Shutdown features have been enabled, the chiller continues to operate under the same
conditions, displaying WARNING – EXCESS SURGE DETECTED . This message is displayed until it is
manually reset with the Warning Reset button in Operator access level. If the Shutdown setpoint
is enabled, when an excess surge condition is detected, a safety shutdown is performed and the
message SURGE PROTECTION - EXCESS SURGE appears.
21 YVAM Control Center