York YCAS0130 manual Alarms, Run Status Chiller, Lead / Lag Compressor Selection

low suction pressure cutout setting or for 180 seconds, whichever comes first. Pump down occurs on “normal” shutdowns where cooling demand has been satisfied or when a system switch is turned off, a flow switch opens, run permissive is lost or a Daily Schedule or a Remote Shutdown is called for.

No pumpdown will occur on a safety shutdown. See page 138 for the pumpdown display message.

1.19ALARMS

Internal contacts are provided in the Micro Panel (See Section 1.12) which can be used to remotely signal a warning whenever a fault lockout occurs on any system or if power is lost to the control panel. The internal contacts are normally open (N.O.) and will close when control power is applied to the panel, if no fault condi- tions are present. When a fault occurs which locks out a system, the respective contacts open. If chiller power is lost or a unit fault occurs, such as a Low Water Temp fault, contacts for all systems will open.

Contacts for SYS 1 are located on the bottom right of the microprocessor panel, terminals 23 and 24. SYS 2 contacts are located on terminals 27 and 28. See Fig. 11, Page 38 for the location of these terminals.

A 28VDC or 120VAC (60 Hz models) or up to 240VAC (50 Hz models) external alarm circuit (supplied by oth- ers) may be connected to these contacts. The contacts are rated at 125VA.

If any inductive load devices (relay or contactor) supplied by the user are in the electrical circuit connected to the dry alarm contacts, the device must be suppressed at the load with a RC suppressor YORK Part Number 031- 00808-000 across the inductive coil. Failure to install suppressors will result in nuisance faults and possible damage to the chiller.

If the alarm circuit is applied in an application used for critical duty (such as process duty or cooling other crit- ical equipment) and the alarm circuit should fail to function, YORK will not be liable for damages.

FORM 201.19-NM1 (204)

1.20RUN STATUS (CHILLER)

Internal Chiller Run Status contacts between Terminal 28 and 29 close whenever one of the systems is run- ning. These contacts are located on the bottom right of the Microprocessor Board and are rated (voltage and current) the same as the alarm contacts (Section 1.19). Also use a suppressor, same as alarm contacts (Section 1.19). Individual system “Run Status” contacts are not available.

1.21LEAD / LAG COMPRESSOR SELECTION

The chiller may be set up for AUTO or MANUAL Lead/ Lag. This is accomplished by programming the option under the Program Key. Details for programming the Manual/Auto Lead/Lag Selection are discussed in Pro- gram Key Section 8, page 169.

When AUTO Lead/Lag is utilized, the micro attempts to balance run time between the two compressors. A number of conditions can occur which will prevent this from happening. Factors determining lead/lag selection and the resulting lead/lag determination are:

1.The micro automatically defaults the lead to SYS 1 and the lag to SYS 2 if both compressors are ready to start (Anti-recycle Timers timed out) and com- pressors have equal run time.

2.If all compressors are ready to start (Anti-recycle timers timed out), the compressor with the lowest run hours will start first.

3.If all compressors are waiting to start (Anti-recycle timers have not timed out), the micro will assign the lead to the compressor with the shortest anti-recycle time in a an effort to provide cooling quickly.

4.If the lead compressor is locked out, faulted and waiting to restart, SYS switch on the microboard is off, or a run permissive is keeping an individual system from running, the lag compressor is swapped to the lead. This is true regardless of whether the lag compressor is ON or OFF.

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YORK INTERNATIONAL 133