189
JOHNSON CONTROLS
FORM 201.21-NM4 (616)
189
JOHNSON CONTROLS
7
0 – 10 VDC Reset Input
A 0 VDC signal produces a 0°F reset. A 10 VDC signal
produces the maximum remote temp reset (program-
mable under the SETPOINTS key). The setpoint reset
is ramped linearly between these limits as the input
varies between 0 VDC and 10 VDC. In order for this
input to work properly, the Remote Temperature Reset
must be programmed for 0 – 10 VDC input (OPTIONS
key) and Chiller Control Board jumper JP4 placed in
the “V” position.
2 – 10 VDC Reset Input
A 0 - 2 VDC signal produces a 0°F reset. A 10 VDC
signal produces the maximum remote temp reset (pro-
grammable under the SETPOINTS key). The setpoint
reset is ramped linearly between these limits as the input
varies between 2 VDC and 10 VDC. In order for this
input to work properly, the Remote Temperature Reset
must be programmed for 2 – 10 VDC input (OPTIONS
key) and Chiller Control Board jumper JP4 placed in
the “V” position.
LOCAL CURRENT LIMIT CONTROL
Local Current Limit Control is used to set the actual Cur-
rent Limit Setpoint. This is accomplished by changing
the Local Current Limit Setpoint under the PROGRAM
key. This is the value at which the unit will begin to
current limit and override capacity control if remote
reset is not actively overriding this control. If any other
current limit methods are active, the lowest value will
be used.
Keep in mind that limiting current may interfere with
capacity control, pulling down chilled liquid tempera-
tures on hot water starts, and maintaining chilled liquid
setpoints.
REMOTE TEMPERATURE RESET CONTROL (CON'T)
0 – 20 mA Reset Input
A 0 mA signal produces a 0°F reset. A 20 mA signal
produces the maximum remote temp reset (program-
mable under the SETPOINTS key). The setpoint reset is
ramped linearly between these limits as the input varies
between 0 mA and 20 mA. In order for this input to
work properly, the Remote Temperature Reset must be
programmed for 0 – 20 mA input (OPTIONS key) and
Chiller Control Board jumper JP4 placed in the “mA”
position.
4 – 20 mA Reset Input
A 4 mA signal produces a 0°F reset. A 20 mA signal
produces the maximum remote temp reset (program-
mable under the SETPOINTS key). The setpoint reset is
ramped linearly between these limits as the input varies
between 4 mA and 20 mA. In order for this input to
work properly, the Remote Temperature Reset must be
programmed for 4 – 20 mA input (OPTIONS key) and
Chiller Control Board jumper JP4 placed in the “mA”
position.
LOCAL CURRENT LIMIT CONTROL
PULLDOWN CURRENT LIMIT SETPOINT
The Pulldown Current Limit Setpoint can be set under
the PROGRAM key. This current limit setpoint is only
active on startup for the time defined by the Pulldown
Current Limit Time under the PROGRAM key. After
the run time has exceeded this time, the Pulldown Cur-
rent Limit Setpoint is ignored.
This control is useful in limiting current pulldown de-
mand during peak usage periods where electric costs
are highest.
Keep in mind that limiting current may interfere with
capacity control, pulling down chilled liquid tempera-
tures on hot water starts, and maintaining chilled liquid
setpoints.
