Shutdown sequences of carrier centrifugal chiller 19 xvr

The shutdown process initiates when the chilled water temperature drops below the control point, minus recycle shutdown delta Tor when the operating schedule shifts to unoccupied or when an alarm condition occurs then the stop button is pressed.

The first two are called recycle shutdowns and the following sequence occurs.-stop signal occurs guide vanes close.

Variable frequency drive if the applicable goes to zero speed.

After starter are verified to be off the oil pump continues to run for 60 seconds to provide lubrication as he compressor coasts down.

A shutdown because a stop button has been pressed is same as the recycle shutdown except that the chiller will not automatically start.

It must be restarted manually using the CCN or the local keys unless the remote contact option is enabled.

A shutdown due to an alarm condition maybe immediate without waiting for the guide vanes to close depending on the severity of the alarm and of course the chiller will not automatically restart from an alarm condition.

Oil pump and condenser pump shuts downs .

Chiller water pump may run or shut off depending or conditions.

While the shutdown sequence is occurring the default screen will show the message "SHUTDOWN IN PROGRESS" and "COMPRESSOR REENERGIZED"

Start up sequences of carrier centrifugal chiller

The chiller has a well defined start-up and shutdown sequence which we need to be familiar with.A start up under a local control can occur after a local key has been pressed at the default screen.

Note:-

if the remote contacts are enabled then the contact status determines if the start up process continues.

Also in order for the start-up to proceed an occupancy made must be specified for present time or an unoccupied mode must be over.

Further at least 1 minute must be lapsed since the last shutdown.

And at least 15 minutes must be lapsed since the last start up.

And it cannot be more than 8 starts in the last 12 hours.

When those conditions are met the control will perform a series of pre start checks to verify that all
safeties are within limits.

30 seconds later point C, the controls start checking the chilled water and condenser water pressure
drops to confirm water flow.

If sufficient pressure drops is not sensed after 5 minutes of checking start up is aborted.

After water flow is verified the actual chilled water temperature is compared to the control point plus the dead band.

If the chilled water temperature is greater than the control point plus the dead band the start up sequence continues on the check that the inlet guide vane is closed.

If they are not the star up is delayed until the vanes are closed .

When the vanes are closed the oil pump is started.

Then point D, the pick waits until the oil pressure is verified with minimum pressure of 18 PSI.

After oil pressure has been verified a 40 second pre loop cycle .At this time the 15 minute start to start timer is activated.

While the start up sequence is under way the default screen will display the messages "START-UP IN PROGRESS" and "OCCUPIED MODE".

When the starting sequence is complete and the system is open running the default screen will display the message "RUNNING" followed by a message indicating any condition that maybe affecting the control point.

If they are one the message will indicate "LEADING CHILLED WATER OR ENTERING CHILLED WATER" depending on which type of control has been configured.