Carrier 48/50Z030-105

117

CONTROL EXPANSION MODULE (CEM) — The optional

CEM is used to provide inputs for demand limiting, remote set

point and other optional inputs typically needed for energy

management systems. See Fig. 29. On CCN systems these

inputs can be interfaced to through the CCN communications.

It is located in the main control box. The CEM also has inputs

for accessory relative humidity sensors. This board is also used

on units equipped with optional outdoor air CFM monitoring.

The inputs and outputs are summarized in Table 91.

The optional (or accessory) CEM is used to accept inputs

for additional sensors or control sequence switches, including:

• Smoke control mode field switches

• VAV supply air set point reset using an external 4 to

20 mA signal

• Outdoor air CO2 sensor

• Space, return and/or outdoor air relative humidity

sensors

• IAQ function discrete switch

• Demand limit sequence proportional signals or discrete

switches

The CEM is factory-installed when the outdoor air cfm con-

trol option is installed.

LOW VOLTAGE TERMINAL STRIP — This circuit board

provides a connection point between the major control boards

and a majority of the field-installed accessories. See Table 92.

The circuit breakers for the low voltage control transformers,

interface connection for the Carrier Comfort Network® (CCN)

communication, and interface connection for the Local Equip-

ment Network (LEN) communication are also located on the

low voltage terminal strip.

INTEGRATED GAS CONTROL (IGC) — One IGC is pro-

vided with each bank of gas heat exchangers. One is used on

low heat size 030-050 units. Two are used on high heat size

030-050 units and low heat 055-105 units. Three are used on

high heat 055-105 units. The IGC controls the direct spark ig-

nition system and monitors the rollout switch, limit switches,

and induced-draft motor Hall Effect switch. The IGC is

equipped with an LED (light-emitting diode) for diagnostics.

See Table 93.

COMPRESSOR PROTECTION BOARD (CSB) (Size 105

Units Only) — This board monitors the status of the compres-

sor by sensing the current flow to the compressors and then

provides digital status signal to the MBB.

ADDRESS DIP

SWITCHES ALL ON

RED LED-

STATUS

GREEN LED-

LEN (LOCAL EQUIPMENT NETWORK)

PWR

LEN

4-POSITION

DIP SWITCH

PWR

113 10 7

XDCR/THERM

7413131

0-20mA OUT

THERMXDCR/THERM

13 10 7RELAYS

CEBD430427 HK50AA032 CEPL130427

Fig. 28 — Staged Gas Heat Control Board (SCB)