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SECTION 1 - FIELD CONTROL MODIFICATIONS
When condenser liquid is flowing, the flow switch
contact will close. Opening the Condenser Liquid Flow
Switch Contacts for 2 continuous seconds will cause
unit shutdown. The flow switch status is continuously
checked from 30 seconds into "System Run". Then the
OptiView™ Control Center will display the following
messages:
• CYCLING SHUTDOWN – AUTO RESTART
• CONDENSER FLOW SWITCH OPEN.
CHILLED LIQUID FLOW SENSORS
The Thermal-type Flow Sensor interfaces with the mi-
croboard and Paddle-type Flow Sensor interfaces with
the I/O board.
For the program to read the appropriate inputs for the
flow sensor status, the actual flow sensor type used
must be entered at the keypad OPERATIONS Screen
using Service the Access Level. Enter "J14" for Ther-
mal-type or "TB" for Paddle-type. Refer to YZ Opera-
tions and Maintenance (Form 161.01-OM1).
When liquid flow is sensed, the flow sensor contacts are
closed. Opening of the flow sensor contacts (no flow)
for 2 continuous seconds causes a cycling shutdown
displaying LEAVING CHILLED LIQUID - FLOW
SWITCH OPEN. The flow sensor status is bypassed
for the first 25 seconds of "System Prelube".
Paddle-type Flow Sensor
12
I/O
Board
1
TB3
Thermal-type Flow Sensor
4
5
2
4
J14-
FIGURE 13 - CHILLED LIQUID FLOW SWITCHES
12
Chilled Liquid
Flow Switch
1
Chilled Liquid
3
Flow Switch
LD23515a
THERMAL TYPE FLOW SENSOR
When the Thermal-type Flow Switch is used, the flow
switch uses the cooling effect of liquid to sense flow.
When the flow of liquid is sensed, the relay output is
turned on conducting current through the microboard
load resistor to the +5VDC, applying greater than
+4VDC to the microboard input J14-4.
When no flow of liquid is sensed, the relay output is
turned OFF, this results in less than 1VDC to the mi-
croboard input.
PADDLE TYPE FLOW SENSOR
When Evaporator water is flowing, the flow switch
con tact will close. If the flow switch opens for 2 sec-
onds, the unit shuts down.
REMOTE MOTOR CURRENT LIMIT SETPOINT
The Remote Motor Current Limit Setpoint can be re-
set within the range of 100% to 30% Full Load Amps
(FLA) by:
• A BAS when an SC-EQ communication card is
installed
• Or, by a hard-wired analog 0-10VDC, 4-20mA or
digital 1-11 second PWM signal (supplied by oth-
ers).
The OptiView™ Control Center must be configured
appropriately to accept the desired signal in the Re-
mote Control Screen (Home>Setpoints>Remote).
• Control Source BAS - The setpoint is communi-
cated by the BAS through the SC-EQ using either
BACnet MS/TP, Modbus RTU or the N2 protocol.
• 0-10V - The reset signal is a 0-10VDC hardwired
signal from the BAS. The Microboard jumper
JP23 must be removed for this setting.
0-10VDC - As shown in Figure 14 on page 13,
connect input to Microboard J22-1 (signal) and J22-
5 (Gnd). The setpoint varies linearly from 100% to
30% FLA as the input varies from 0-10VDC. This
input will only be accepted when the Control Source
is set to 0-10. A signal of 0VDC = 100%, a signal of
10VDC = 30%.
Calculate the setpoint for various inputs as follows:
SETPOINT (%) = 100 – (VDC X 7)
FORM 161.01-PW2
ISSUE DATE: 7/18/2018
JOHNSON CONTROLS
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