Sub-Zero 700TC-3 Service Manual page 26

Electronic Control System
Assist in Control of Variable Speed Compressors (700TF/I-3 Only)
As mentioned on the previous page, temperature signals from the thermistors in the compartment are monitored by
the microprocessor and then displayed on the LCD.
When the compartment reaches high-offset (calling for cooling), an "ON" signal is sent from the control board to the
compressor's inverter. The inverter (which is supplied with AC power at all times) then provide high DC voltage (3-
phase, 50 - 150 Hz), outputs to the compressor. The inverter in turn senses the compressor load. If the compressor
load is high, the speed command from the inverter will be for high speed compressor operation; if medium compres-
sor load, speed command from the inverter will be for medium speed; if low compressor load, speed command from
the inverter will be for low speed. If/when the compartment reaches low-offset, an "OFF" signal is sent to the invert-
er, which then cuts DC power to the compressor.
NOTE:
• The variable speed compressor, evaporator fan and the condenser fan will run a great majority of the time. This is
normal. These components will only cycle off during defrost and may also cycle off for short periods of time if the
ambient temperature is low enough.
• Initial speed command from an inverter to a compressor are always for High speed.
NOTE: Line voltage
supplied to inverter
at all times.
HIGH VOLTAGE
J5
J7
E2 E7 E10 E6
J3
J2
2. When cooling is called for,
115 Volts AC "ON" signal
supplied to compressor
inverter, evaporator fan
and condenser fan.
Figure 3-21. 700TF/I-3 Signal Trace Schematic of Variable Speed Compressor Operation
#3758412 - Revision B - December, 2006
LOW VOLTAGE
DISPLAY
J5
0
PIN 1
PIN 1
J7
0
E2 E7 E10 E6
J4
J3
PIN 1
PIN 1
PIN 1
J2
0
J1
0 0
115 VOLTS
L1 NEUT
60 CYCLES
BLACK
WHITE
BLACK
J6
PURPLE
J4
J1
Integrated
Integrated
(700-
(700-
J6 MEMBRANE SWITCH
0
PIN 1
0
PIN 1
BLUE W/BLACK STRIPE
BLUE W/BLACK STRIPE
WHITE
CONDENSER
FAN MOTOR
M
FREEZER
FAN SWITCHES
PURPLE
3-12
3
3 Series
Series
T ALL)
T ALL)
1. Compartment
temperature
monitored by
microprocessor
FRZ CAB
THERMISTOR
VSPEED
CONTROL
LT. BLUE
BROWN
BOX
BLACK
FREEZER
FAN MOTOR
RED
M
IN EXCESS OF 200 VOLTS MAY
BE PRESENT AT INVERTER
AND COMPRESSOR!
3. Inverter supplies
high DC voltage,
3-phase, 50 - 150
Hz signal, based
on compressor
load.