Carrier HS070-160 - Manual (Page 2)

Features The control panel is shown in
Fig. 1.
PROCESSOR MODULE
This module contains the
operating software and controls the operation of the
machine. It continuously monitors information received
from the various temperature thermistors and communi-
cates with the relay module to increase or decrease the
active stages of capacity. The processor module also
controls the EXV driver module, commanding it to open
or close each electronic expansion valve in order to main-
tain approximately 20 F of superheat t h e
cylinders of each of the compressors, Information is
transmitted between the processor module and the relay
module, EXV driver a n d k e y b u a r d d i s p l a y
module through a 3-wire communications bus.
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EXV (ELECTRONIC EXPANSION DRIVER
MODULE -- The EXV driver module operates the elec-
tronic expansion valves (based on commands from the
processor) and monitors the status of the
pressure
switches and the refrigerant Ioss of charge switches.
If the loss of charge switch opens due to a low refrig-
erant charge, the EXV driver module detects a zero
voltage condition in the loss of charge switch electrical
circuit and communicates this information to the pro-
cessor module. The processor module immediately shuts
down all compressors in the affected refrigeration circuit.
During operation, if the EXV driver module detects
zero voltage in the oil pressure switch electrical circuit
for 45 consecutive seconds (due to an open oil pressure
switch), it communicates this information to the pro-
cessor module. The processor module
down
compressors in the affected refrigeration
At start-up, if the oil pressure switch has not closed by the
end of a
time period the EXV driver module
senses this and the processor module immediately shuts
down all compressors in the affected refrigeration circuit.
If a shutdown occurs due to loss of or low oil
pressure, the EXV module communicates this to
the processor module and the processor module locks the
compressors off in the affected refrigeration circuit.
The proper fault code(s) will appear on the display
whenever a safety switch opens.
KEYBOARD AND DISPLAY (Fig. 2)
This device consists of a keyboard with function keys,
5 operative keys, 12 numeric keys (0 to and an
alphanumeric g-character LCD. Key
explained
in Table
Table 1 Keyboard and Display
Key Usage
FUNCTION
K E Y S
Module
Control Power ON Light
3 RUN/STANDBY Switch
Discharge Pressure Gage
5 Suction Pressure Gage Valves
Suction Pressure Gages
7 Discharge Pressure Gages
8 Compressor ON Lights
9 Control Circuit Fuses
10 Alarm Light
OPERATIVE
Fig. 1 Control Panel K E Y S
qCLR
LOW-VOLTAGE RELAY MODULE -- This module
closes contacts to compressors, solenoid valves
and unloaders. It also senses the condition of the com-
pressor safeties and transmits this information to the
processor module.
q
Status diagnostic
codes and
information about the machine
Quick Test Checking inputs
and outputs for proper
operation
History This key appears on
the keyboard, but is not used on
the
E machines
Service Entering specific
unit configuration information
Set Point Entering operating
set points and day/time
information
Schedule Entering occupied/
unoccupied schedules for unit
operation
USE
Expand Display Displaying a
non-abbreviated expansion of
the display
Clear Clearing the screen of
all displays
Up Arrow
previous display
Down Arrow Advancing to
next display position
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