Carrier Ecologic 30GX080 Series Controls, Start-Up, Operation, Service, And Troubleshooting Download Page 3

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6 thermistors, and up to 10 transducers. A remote enhanced
display is available as an accessory.

MAJOR SYSTEM COMPONENTS

Processor Module (PSIO-1) —

This module is an

upgrade to the original PSIO (8088) module, with superior
electrical noise immunity capability. It contains the operating
software and controls the operation of the machine. It has 12
input channels and 6 output channels.

The PSIO-1 continuously monitors input/output channel in-

formation received from all the modules and controls all output
signals for all output channels. It also controls the relays on the
six-pack relay board. The processor module also controls the
EXD driver module, commanding it to open or close each
EXD in order to maintain the proper cooler level. Information
is transmitted between the processor module, CPM modules,
the EXD driver module, and the HSIO-II standard display
module through a 3-wire communications bus called COMM3.
The remote enhanced display (accessory) is connected to the
PSIO-1 module through a 3-wire communications bus, but
uses a different communication bus called COMM1. The
COMM1 bus is also used to communicate to other CCN
(Carrier Comfort Network) devices when the unit is installed in
a network application.

DSIO-HV Relay Module —

The DSIO-HV module has

4 inputs and 8 outputs and is installed on 30GX units only. The
module communicates the status of the inputs with the PSIO-1
module and operates the oil heater, outdoor fan, and minimum
load control outputs.

Electronic Expansion Device Module —

The

electronic expansion device module has 4 inputs and 2 outputs.
It receives signals from the PSIO-1 module and operates the
electronic expansion devices. The electronic expansion device
module also sends the PSIO-1 module the status of its 4 input
channels.

Compressor Protection Module (CPM) —

The

compressor protection module monitors the high pressure
switch status, running current, and motor temperature for each
compressor. Each CPM controls up to 2 compressors. The
CPM also controls the motor cooling solenoid, oil solenoid,
and contactor outputs. A pre-punched configuration header for
each compressor determines the must trip amps setting. Each
CPM sends the PSIO-1 each compressor’s motor temperature,
relay status, and running current as a percentage of the must
trip amps value. The CPM also communicates any alarm con-
ditions as the feedback value.

PSIO-2 (8052) Module —

This module is used as an in-

put/output module only, as there is no unit software loaded in
the module. This module has 12 input channels and 6 output
channels.

Keypad and Display Module (Also Called
HSIO-II) —

This device consists of a keypad with 8 function

keys, 4 operative keys, 12 numeric keys, and a 2-line
24-character alphanumeric LCD (liquid crystal display). Key
usage is explained in the Accessing Functions and Subfunc-
tions section on page 15.

Control (LOR) Switch —

Control of the chiller is de-

fined by the position of the LOCAL/OFF/REMOTE (LOR)
switch. This is a 3-position manual switch that allows the chill-
er to be put under the control of its own controls (LOCAL),
manually stopped (OFF), or controlled through a set of remote
contacts (REMOTE). This switch is different than the switch

that is used in the Flotronic™ II controls configuration. The
CCN control is enabled through the HSIO-II. The switch al-
lows unit operation as shown in Table 1.

In the LOCAL position, the chiller is allowed to operate and

respond to the scheduling configuration, CCN configuration,
and set point data. In the remote position, the unit operates sim-
ilarly to the LOCAL position, except the remote contacts must
be closed for the unit to operate.

Table 1 — Unit Mode from LOR Switch

and CCN State

LEGEND

NOTE: If the unit is configured for a clock, then the unit is under clock control if it is in an
ON mode.

OPERATION DATA

Electronic Expansion Device (EXD) —

The micro-

processor controls the EXD through the EXD driver module.
The EXD will either be an EXV (electronic expansion valve) or
an economizer. Inside both these devices is a linear actuator step-
per motor.
EXV OPERATION — High-pressure liquid refrigerant en-
ters the valve through the bottom. A series of calibrated slots
are located inside the orifice assembly. As refrigerant passes
through the orifice, the pressure drops and the refrigerant
changes to a 2-phase condition (liquid and vapor). To control
refrigerant flow for different operating conditions, the sleeve
moves up and down over the orifice, thereby changing orifice
size. The sleeve is moved by a linear stepper motor. The step-
per motor moves in increments and is controlled directly by the
processor module. As the stepper motor rotates, motion is
transferred into linear movement by the lead screw. Through
the stepper motor and lead screw, 1500 discrete steps of motion
are obtained. The large number of steps and long stroke result
in very accurate control of refrigerant flow.

Each circuit has a liquid level sensor mounted vertically in

the top of the cooler shell. The level sensor consists of a small
electric resistance heater and 3 thermistors wired in series, po-
sitioned at different heights inside the body of the well. The
heater is designed so that the thermistors read approximately
200 F (93.3 C) in dry air. As the refrigerant level rises (falls) in
the cooler, the resistance of the closest thermistor(s) will in-
crease (decrease) as it is cooled by the rising liquid refrigerant
(heated by the heater). This large resistance difference allows
the control to accurately maintain a specified level.

The level sensor monitors the refrigerant liquid level in the

cooler and sends this information to the PSIO-1. At initial start-
up, the EXV position is at zero. After that, the microprocessor
keeps accurate track of the valve position in order to use this in-
formation as input for the other control functions. The proces-
sor does this by initializing the EXVs at start-up. The processor
sends out enough closing pulses to the valve to move it from
fully open to fully closed, then resets the position counter to ze-
ro. From this point on, until the next initialization, the proces-
sor counts the total number of open and closed steps it has sent
to each valve.

SWITCH

POSITION

REMOTE

CONTACTS

CCN

CONFIGURATION

CCN

STATE

UNIT

MODE

LOCAL

DISABLE