JOHNSON CONTROLS
94
FORM 160.79-O3
ISSUE DATE: 11/09/2018
SECTION 2 – OPTIVIEW CONTROL CENTER
Motor Current Limit Setpoint
Displays the current limit being applied to compressor
#1 motor.
If both compressor motors are running, it displays the
active Chiller Current Limit value.
If only compressor motor #1 is running:
• If the Lead Compressor Pulldown Time Setpoint
is in effect, it is the Lead Compressor Pulldown
Demand Limit Setpoint value.
• If the Lead Compressor Pulldown Time Setpoint
is not in effect, it is twice the Chiller Current Lim-
it, up to 100%.
Operating Hours
Displays the total accumulated run time of compressor
#1.
Number of Starts
Displays the total accumulated number of starts of
compressor #1.
Run Time
Displays the amount of time in days, hours and min-
utes that compressor #1 motor has been running since
the last start signal was received. Value is reset to zero
when compressor #1 enters Coastdown. It remains at
zero while shutdown.
PROGRAMMABLE
Local Chiller Current Limit
Access Level Required: OPERATOR
Allows the user to specify the maximum allowed
Chiller Current. The Chiller Current is the total mo-
tor current being conducted by the chiller. If only one
compressor motor is running, that is the Chiller Cur-
rent. If both compressor motors are running, the Chiller
Current is the total of both motors, with the Pre-rota-
tion Vanes operated to achieve equal current to both
motors. The Chiller Full Load Amps (FLA) is the total
of compressor #1 motor and compressor #2 motor FLA
ratings, with each motor having an equal FLA rating.
For example, if the Chiller FLA is 1600 amps, the FLA
of each motor is 800 amps. The Chiller Current Limit
Setpoint is expressed as a percentage (30% to 100%)
of Chiller FLA. In this example, the chiller FLA is
1600 amps. If the Chiller Current Limit Setpoint is set
at 70%, the Chiller Current is limited to 1120 amps.
If only one motor is running, the Motor Current Limit
(see Motor Current Limit Setpoint above) for that mo-
tor would be set to 100% and it would be allowed to
operate at its maximum of 800 amps, However, if both
motors are running, each would be limited to 560 amps
per motor, producing a Chiller Current of 1120 amps.
This setpoint is in effect after the Lead Compressor
Pulldown Time setpoint (see below) has elapsed and
for the remainder of system run.
Lead Compressor Pulldown Demand Limit
Access Level Required: OPERATOR
Allows the user to specify a motor current limit (30%
to 100% FLA) that’s applied to the Lead compres-
sor motor during the time period programmed as the
LEAD COMPRESSOR PULLDOWN TIME Setpoint.
This current limit applies to the full load amps of the
Lead compressor motor only, not the Chiller Full Load
Amps (total of both compressors). For example, if the
Chiller Full Load Amps is 2000 A, then each compres-
sor’s FLA is 1000 A. If set to 80%, then the lead com-
pressor motor current would be limited to 800 A (80%
x 1000) for the duration of this period.
Lead Compressor Pulldown Time
Access Level Required: OPERATOR
This setpoint is used to limit the chiller to single com-
pressor operation for a specified duration (0-255 min-
utes) when starting the chiller. While this pulldown
time is in effect, “System in Lead Compressor Pull-
down” is displayed on the system details line along
with the time remaining in the period. During this time,
only the lead compressor is permitted to run. The lag
compressor will not be brought on line. After this time
has elapsed, the lag compressor can be brought on line
per normal operation. While this period is in effect, the
lead compressor motor current will be limited to the
value programmed for the
Lead Compressor Pull-
down Demand Limit
Setpoint (30-100% FLA).
After the Lead Compressor Pulldown Time Setpoint
has elapsed, the chiller current limit will be limited to
the value programmed for the Current Limit Setpoint.
