7
F100d
JAN 2011
FROST MASTER®
PLUS
RELAY OPERATION
CONTROL VALVE
OR RELAY
RELAY
DEFROST STEPS
NORMAL
REFRIG.
PUMPOUT
SOFT GAS*
HOT GAS
EQUALIZE
FAN DELAY
Liquid Solenoid
L
Suction Solenoid
S
Soft Gas Solenoid
SG
Hot Gas Solenoid
H
Equalize Solenoid
E
Fan Motor Relay
F
The table above indicates the relay positions during each defrost step and normal refrigeration.
* There is approximately a 5 second delay before the “SG” relay switches to its position during this step. This
is to give the suction solenoid valve time to close before the soft gas solenoid valve opens.
WIRING DIAGRAM
The wiring diagram below is typical for the bottom feed evaporator shown on page 9. Other wiring schemes
are possible to meet system requirements. This wiring diagram is for illustration purposes only and does not
show all controls and safety devices. Final control wiring is the responsibility of the system designer. See
above table for relay operation.
Relays shown with no power to Frost Master® Plus. See above for relay operation.
= RELAY ENERGIZED
POWER
INPUT
RELAY L
RELAY S
NC
NC NO C
NO
RELAY SG
C
C
NO
NC
C
NO
NC
C
NO
NC
RELAY H
RELAY E
HOT GAS SOLENOID VALVE
LIQUID SOLENOID VALVE
N
L
EQUALIZE SOLENOID VALVE
CONVENTIONAL SUCTION SOLENOID VALVE
FIELD
INSTALLED
5 AMP FUSE
INIT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
OPTIONAL
DEFROST
INITIATE
DEVICE
HOT GAS
TERMINATE
TEMP.
SENSOR
20
19
18
RELAY F
NC NO C
FAN MOTOR RELAY
SOFT GAS SOLENOID VALVE
PILOT SOLENOID VALVE TO GAS-POWERED SUCTION STOP VALVE
