Carrier 30RAP010-060 specifications Controls, Control Module Communication

CONTROLS

General — The 30RAP air-cooled scroll chillers contain the ComfortLink™ electronic control system that controls and monitors all operations of the chiller.

The control system is composed of several components as listed in the sections below. See Fig. 3-5 for typical control box drawings. See Fig. 6 and 7 for control schematics.

Main Base Board (MBB) — See Fig. 8. The MBB is the heart of the ComfortLink control system. It contains the major portion of operating software and controls the operation of the machine. The MBB continuously monitors input/output channel information received from its inputs and from all other modules. The MBB receives inputs from the discharge and suction pressure transducers and thermistors. See Table 15. The MBB also receives the feedback inputs from each compressor current sensor board and other status switches. See Table 16. The MBB also controls several outputs. Relay outputs con- trolled by the MBB are shown in Table 17. Information is transmitted between modules via a 3-wire communication bus or LEN (Local Equipment Network). The CCN (Carrier Com- fort Network) bus is also supported. Connections to both LEN and CCN buses are made at the LVT (low voltage terminal). See Fig. 8.

Energy Management Module (EMM) — The EMM module is available as a factory-installed option or as a field- installed accessory. The EMM module receives 4 to 20 mA inputs for the leaving fluid temperature reset, cooling set point and demand limit functions. The EMM module also receives the switch inputs for the field-installed2-stage demand limit and ice done functions. The EMM module communicates the status of all inputs with the MBB, and the MBB adjusts the control point, capacity limit, and other functions according to the inputs received.

Current Sensor Board (CSB) — The CSB is used to monitor the status of the compressors by measuring current and providing an analog input to the main base board (MBB) or compressor expansion module (CXB).

AUX Board (AUX) — The AUX is used with the digital scroll option and the low ambient head pressure option. It pro- vides additional inputs and outputs for digital scroll control along with analog outputs to control head pressure control fan speeds.

Expansion Valve Board (EXV) — The EXV board communicates with the MBB and directly controls the expan- sion valves to maintain the correct compressor superheat.

Enable/Off/Remote Contact Switch — The Enable/ Off/Remote Contact switch is a 3-position switch used to control the chiller. When switched to the Enable position the chiller is under its own control. Move the switch to the Off position to shut the chiller down. Move the switch to the Remote Contact position and a field-installed dry contact can be used to start the chiller. The contacts must be capable of handling a 24 vac, 50-mA load. In the Enable and Remote Contact (dry contacts closed) positions, the chiller is allowed to operate and respond to the scheduling configuration, CCN configuration and set point data. See Fig. 9.

Emergency On/Off Switch — The Emergency On/Off switch should only be used when it is required to shut the chiller off immediately. Power to the MBB, EMM, and marquee display is interrupted when this switch is off and all outputs from these modules will be turned off.

Board Addresses — The main base board (MBB) has a 3-position instance jumper that must be set to ‘1.’ The elec- tronic expansion valve board (EXV) and energy management board (EMM) have 4-position DIP switches. All switches are

set to ‘On’ for these boards. The auxiliary board (AUX) has an 8-position DIP switch. Switches 2, 5, and 7 are set to ‘On.’

Control Module Communication

RED LED — Proper operation of the control boards can be visually checked by looking at the red status LEDs (light-emitting diodes). When operating correctly, the red status LEDs should be blinking in unison at a rate of once every 2 seconds. If the red LEDs are not blinking in unison, verify that correct power is being supplied to all modules. Be sure that the main base board (MBB) is supplied with the current soft- ware. If necessary, reload current software. If the problem still persists, replace the MBB. A red LED that is lit continuously or blinking at a rate of once per second or faster indicates that the board should be replaced.

GREEN LED — The MBB has one green LED. The Local Equipment Network (LEN) LED should always be blinking whenever power is on. All other boards have a LEN LED which should be blinking whenever power is on. Check LEN connections for potential communication errors at the board J3 and/or J4 connectors. Communication between modules is accomplished by a 3-wire sensor bus. These 3 wires run in parallel from module to module. The J4 connector on the MBB provides both power and communication directly to the marquee display only.

YELLOW LED — The MBB has one yellow LED. The Carrier Comfort Network (CCN) LED will blink during times of network communication.

Carrier Comfort Network® (CCN) Interface —

The 30RAP chiller units can be connected to the CCN if desired. The communication bus wiring is a shielded, 3-conductor cable with drain wire and is supplied and installed in the field. See Table 18. The system elements are connected to the communication bus in a daisy chain arrangement. The positive pin of each system element communication connector must be wired to the positive pins of the system elements on either side of it. This is also required for the negative and signal ground pins of each system element. Wiring connections for CCN should be made at LVT. Consult the CCN Contrac- tor’s Manual for further information.

NOTE: Conductors and drain wire must be 20 AWG (Ameri- can Wire Gage) minimum stranded, tinned copper. Individual conductors must be insulated with PVC, PVC/nylon, vinyl, Teflon, or polyethylene. An aluminum/polyester 100% foil shield and an outer jacket of PVC, PVC/nylon, chrome vinyl, or Teflon with a minimum operating temperature range of –20 C to 60 C is required. Wire manufactured by Alpha (2413 or 5463), American (A22503), Belden (8772), or Columbia (02525) meets the above mentioned requirements.

It is important when connecting to a CCN communication bus that a color coding scheme be used for the entire network to simplify the installation. It is recommended that red be used for the signal positive, black for the signal negative, and white for the signal ground. Use a similar scheme for cables contain- ing different colored wires.

At each system element, the shields of its communication bus cables must be tied together. If the communication bus is entirely within one building, the resulting continuous shield must be connected to a ground at one point only. If the commu- nication bus cable exits from one building and enters another, the shields must be connected to grounds at the lightning suppressor in each building where the cable enters or exits the building (one point per building only). To connect the unit to the network:

1.Turn off power to the control box.

2.Cut the CCN wire and strip the ends of the red (+), white (ground), and black (–) conductors. (Substitute appropri- ate colors for different colored cables.)

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