Ems/Bas Connections - York MILLENNIUM YCAS Installation Operation & Maintenance

Micropanel
A single phase protection circuit located in the module
also monitors for a phase imbalance. If current imbal-
ance exceeds 17% of the average motor current in one
of the phases, the Motor Protector will recognize it and
shut the system down.
Whenever the Motor Protector Module senses a fault,
internal contacts will open and shut the system down.
These contacts are wired in series with the compressor
motor contactor. When the contact opens, the micro
will attempt to start the system 2 more times. Since the
motor contactor signal path from the Relay Output
Board to the motor contactor is broken by the Motor
Protector Module contacts, it will lock the system out
after 3 faults. The Motor Protector Module must then
be reset by removing 115VAC power from the Control
Panel. After the Motor Protector is reset, the individual
system SYS switch must be switched OFF and then
ON to reset the microprocessor to allow restart of the
system. NOTE: Anytime the module faults, a thorough
investigation of the problem should be performed be-
fore attempting to return the system to operation. Fail-
ure to perform this investigation could lead to motor or
compressor failure. Additional details on the Motor Pro-
tector Module can be found on page 18.
1.10 EMS/BAS CONTROLS
The microprocessor system can accept remote signals
to Start/Stop the chiller, to adjust maximum allowable
running current for each compressor, and to adjust the
chilled liquid leaving temperature setpoint. These func-
tions can easily be controlled by connecting user sup-
plied "dry" contacts to the customer terminals in the
control panel. In addition, Alarm Contacts are provided
to remotely signal a fault with the chiller.
Remote Start/Stop
Remote Start/Stop can be accomplished using a time
clock, manual contact or other "dry" contact in series
with the flow switch (Terminals 13 & 14 of TB4) con-
nected to terminals in the logic section of the control
panel. The contact must be closed to allow the chiller to
run. Any time the contact opens, the chiller will shut
down and the NO RUN PERM message will be dis-
played. The location of the flow switch connection is
shown in Section 1.12.
Never bypass a flow switch. This will
cause damage to the chiller and void
any warranties.
102
Wiring from remote "dry" contacts (for
stop/start reset functions) should not
exceed 8 m (25 ft.) and should be run
in grounded conduit that does not
carry any wiring other than control
wiring or in shielded cable. If an in-
ductive device (relay, contactor) is sup-
plying these contacts, the coil of the
device must be suppressed with a stan-
dard RC suppressor (50Hz models)
across the inductive coil.
Remote Current Reset
The maximum allowable running current for each com-
pressor can be adjusted remotely to a lower value using
repeated timed closure of "dry" contacts connected to
Terminals 13 & 16 at the bottom center of the Micro-
processor Panel (See Section 1.12) in the logic section
of the control panel. The duration of the contact closure
will determine the amount of adjustment. Generally, this
input is used for purposes of demand limit and operates
as follows :
Closing the input contact for a defined period of time
allows reset of the % Current Limit downward. Con-
tact closure of 1 - 11 seconds will allow % Current Lim-
iting to be adjusted downward from 105% by a maxi-
mum of 75%, i.e. to a minimum value of 30% FLA.
EMS Current Limiting operates independently of the
High Average Current Unload (See Section 8.2). The
micro will always look at the two Current Limit Setpoints
and choose the lower as the controlling value, when-
ever Remote Current Limiting is utilized. Contact clo-
sures of less than 1 second will be ignored. A closure of
11 seconds is the maximum allowable closure and pro-
vides a Current Limit reduction of 75%. The remote
reset current can be calculated as follows:
REMOTE
= - {
RESET 105% FLA (Contact Closed Time -1sec)
CURRENT 10 sec
For example, after a 4 second pulse, the offset would
equal:
Remote Reset Curr = 105% FLA - {(4sec - 1 sec) X (75%FLA)}
= 105% - 225%FLA sec
= 82.5% FLA
x
(75% FLA)
10 sec
10 sec
YORK INTERNATIONAL
}