York 371-01200-010, Operating & Maintenance, Page: 10 / 60

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YORK INTERNATIONAL
quired to program the line voltage range. The line volt-
age range is used to determine a low line voltage thresh-
old for cycling shutdown. Refer to “System Setpoints”
for Trip/Reset values.
To Display CONDENSER LIQUID TEMPERATURES:
Use CONDENSER LIQUID TEMPS display key as
described above to produce the following alphanumeric
display message:
COND LEAVING = XXX.X°F; RETURN = XXX.X°F
NOTE: If the condenser liquid thermistors are not con-
nected, or both thermistors are “out of range”,
the display will blank when this key is pressed.
To Initiate a PRINT to Printer:
Press the PRINT key to initiate a printout to an optional
printer. When the key is pressed,
PRINT ENABLE
is displayed.
Refer to “MicroComputer Control Center – System Sta-
tus Printers” instruction, Form 160.49-N2 for details of
the optional printers.
To Display MOTOR CURRENT :
Press the % MOTOR CURRENT display key as de-
scribed above to display motor current as a percent of
Full Load Amps (FLA). The message is as follows:
MOTOR CURRENT = XXX% FLA
NOTE: Liquid-Cooled Solid State Starter Applications
– the % Motor Current displayed is the highest
of three line currents divided by the pro-
grammed chiller FLA value x 100%.
Electro-Mechanical Starter Applications – the
% Motor Current displayed is the highest of the
three line currents.
To Display OPERATING HOURS and STARTS
COUNTER :
Use the OPERATING HOURS key as described on
page 8, to produce the following message:
OPER. HOURS = XXXXX; START COUNTER = XXXXX
NOTE: The operating hours and starts counter can be
reset to zero. Refer to “Programming the Mi-
croComputer Control Center”, page 14. How-
ever, the purpose of the OPERATING HOURS
key is to display the total accumulated chiller
run time. Therefore, the operating hours should
not be arbitrarily reset.
SYSTEM SETPOINTS
The system setpoints may be programmed by the
system operator. The Setpoints keys are located on
the Control Center keypad (see Fig. 3). To program,
see “Programming System Setpoints”, page 14. The
following is a description of these setpoints (with the
English/Metric jumper installed on the Micro Board):
CHILLED LIQUID TEMP – This key displays the leav-
ing chilled water temperature (LCWT) setpoint in de-
grees Fahrenheit. If not programmed, the default value
is 45°F. See “Programming System Setpoints”, page
15).
NOTE: If an Energy Management System is interfaced
to the Control Center for the purpose of remote
LCWT setpoint reset, then the operator-pro-
grammed chilled liquid temperature will be the
base or lowest setpoint available to the Energy
Management System (EMS). This chilled liq-
uid temperature value must also be entered into
the EMS. Further, any subsequent change to
this value must also be entered into the EMS.
% CURRENT LIMIT – This key displays the maximum
value of motor current permitted by its programmed
setting. The value is in terms of percent of Full Load
Amps (FLA). If not programmed, the default value is
100%. (See “Programming System Setpoints”, page
15.)
If chiller is equipped with a YORK Solid State Starter, the
system FLA is also displayed. This value is programmed
by the factory and should never be changed. The Micro
Board uses this value to calculate and display the % mo-
tor current parameter that is displayed when the % MO-
TOR CURRENT display key is pressed. Also, proper cur-
rent limit control depends on the correctly programmed
FLA value. For security reasons, a special access code
is required to program the FLA value. It should only be
changed by a service technician.
PULL DOWN DEMAND – This function is used to pro-
vide energy savings following the chiller start-up. This
key displays a programmable motor current limit and a
programmable period of time. Operation is as follows:
Whenever the system starts, the Pull Down Demand
Limit is maintained for the programmed time, then the
current limit control returns to % current limit setpoint.