Carrier MPE62L-10R, 48MPD Control System, Components, Index of Lead/Lag Circuits Compressors

8.Once the submaster loop is adjusted, remove all forced values and proceed with veri®cation and adjustment of master loop.

9.To check the master loop:

Create a demand in the master loop. For example: Force the actual space temperature to a value less than the heat- ing set point or greater than the cooling set point.

10.Observe system (loop) response for 10 to 20 minutes to verify stable control. After 10 minutes, if the output con- tinues to swing from full open to full closed, lower the MLG and observe again.

11.Do this until the loop operation is stable. After 10 min- utes, if the loop does not seem to respond (little change in submaster reference), increase the MLG and observe again. Do this until stable operation is achieved.

12.Once satis®ed with loop operation, remove all forced values which may have been initiated during this procedure.

13.Repeat Steps 1-12 until all loops have been checked.

NOTE: For better tuning, the building supervisor or service tool should be used to adjust the proportional and integral terms. Contact your Carrier representative for more details.

IAQ Control Loop Adjustment Ð The IAQ (indoor air quality) control loop is different from the other control loops. It has one gain value that can be adjusted in the serv-

ice subfunction ( ) under IAQG (indoor-air quality

gain). This gain is used to speed up or slow down the response of the economizer dampers to the difference be- tween the IAQ set point and the IAQ sensor. If the econo- mizer is moving too slowly, then the gain needs to be increased. If the economizer moves too rapidly and over- shoots the set point, then the gain should be reduced.

Lead/Lag Circuits Ð Lead/lag circuits and compres- sors are shown in Table 20.

Table 29 Ð Index of Lead/Lag Circuits and

Compressors

UNIT 48/50MP	62L	70M	82N, 90P, 10R
LEAD CIRCUIT	A	A	A
Compressor, Lead	A1	A1	A1
Compressor, Lag	*	A2	A2
LAG CIRCUIT	B	B	B
Compressor, Lead	B1	B1	B1
Compressor, Lag	*	*	B2

*Circuit only has 1 compressor.

Final Checks Ð Ensure all safety controls are opera- ting, control panel covers are on, and the service panels are in place.

Recheck all set points against project speci®cations. Com- plete Start-Up Checklist and record operating values. Leave completed checklist with unit for future reference.

NOTE: If the REMOTE START function is used in this ap- plication, set the LOCAL/REMOTE switch to REMOTE (On) at the end of start-up.

CONTROL SYSTEM

General Ð The control system consists of the following components:

·standard processor module (PSIO 8088 or PSIO1)

·options processor module (PSIO 8052 or PSIO2)

·two standard high-voltage relay modules (DSIO-HV or DSIO1 and DSIO2)

·keypad and display module (HSIO or LID)

·enthalpy sensor

·thermistors

·pressure transducers

·accessory humidity sensors

·space temperature sensors (standard T55 and accessory T56)

·supply-air fan status switch

·check ®lter switch

Components

PROCESSOR MODULE NO. 1 Ð The PSIO1 module moni- tors and processes the following inputs, outputs, and system information:

Inputs:

·transducers

·thermistors

·switches

Outputs:

·condenser-fan contactors

·integrated economizer motor (4 to 20 mA)

·optional supply duct static pressure control (VFD) (4 to 20 mA)

·optional modulating power exhaust control (VFD) (4 to 20 mA)

System Information:

·generates alert and alarm information (via transducer, ther- mistor, and sensor inputs)

·supports CCN level II communications

·supports digital air volume (DAV) interface

NOTE: The correct module address for the PSIO1 is 01 (S1 set at 0; S2 set at 1).

PROCESSOR MODULE NO. 2 Ð The PSIO2 module sup- ports the sensors used for:

·humidity control

·outdoor-air cfm

·indoor-air quality (IAQ)

·smoke control

·superheat monitoring (only when accessory transducer ther- mistor kit is ®eld-installed).

In addition, the PSIO2 supplies the outputs for humidity and hydronic heating coil control and a discrete output with timed clock control (for outdoor building or parking lot lights).

NOTE: The correct module address for the PSIO2 is 31 (S1 set at 3; S2 set at 1).

HIGH-VOLTAGE RELAY MODULES (DSIO) Ð The DSIO modules close contacts to energize evaporator and con- denser fan contactors. The modules also control compressor unloaders, compressor contactors, compressor crankcase heat- ers, heat interlock function, and power exhaust contactor. The compressor status through the compressor lockout (CLO) relays and high-pressure switches (safety circuits) are the in- puts to these modules.

NOTE: The correct module addresses for the DSIO1 and DSIO2 modules are 19 and 49, respectively. Set the switch closest to the mounting plate at 1 (DSIO1) or 4 (DSIO2), and the other switch at 9 (both modules).

42