Trane Model 012 GEH Features and Benefits, Deluxe Controls, Microprocessor Design, Generic Relay

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Features and Benefits

Deluxe Controls

Microprocessor Design

The 24 volt deluxe design is a micro- processor-based control board conve- niently located in the control box. The board is unique to Trane water-source products and is designed to control the unit as well as provide outputs for unit status and fault detection.

The Trane microprocessor board is fac- tory wired to a terminal strip to provide all necessary terminals for field connec- tions. See Figure 27 for the deluxe 24V control board.

Deluxe 24V features include: Random Start

The random start relay provides a time delay start-up of the compressor when cycling in the occupied mode. A new start delay time between 3 and 10 sec- onds is applied each time power is enabled to the unit.

Anti-short Cycle Timer

The anti-short cycle timer provides a three minute time delay between com- pressor stop and compressor restart.

Brown-out Protection

The brown-out protection function measures the input voltage to the con- troller and halts the compressor opera- tion. Once a brown-out situation has occurred, the anti-short cycle timer will become energized. The general fault contact will not be affected by this con- dition. The voltage will continue to be monitored until the voltage increases. The compressors will be enabled at this time if all start-up time delays have expired, and all safeties have been sat- isfied.

Compressor Disable

The compressor disable relay provides a temporary disable in compressor operation. The signal would be provid- ed from a water loop controller in the system. It would disable the compres-

sor because of low water flow, peak limiting or if the unit goes into an unoc- cupied state. Once the compressor has been disabled, the anti-short cycle time period will begin. Once the compressor disable signal is no longer present, and all safeties are satisfied, the control will allow the compressor to restart.

Generic Relay

The generic relay is provided for field use. Night setback or pump restart are two options that may be wired to the available relay. (Note: Night setback is available as factory wired). An external Class II 24VAC signal will energize the relay coil on terminals R1 and R2. Terminals C (common), NO (normally open), and NC (normally closed) will be provided for the relay contacts.

Safety Control

The deluxe microprocessor receives separate input signals from the refriger- ant high pressure switch, low suction pressure switch and condensate over- flow.

In a high pressure situation, the com- pressor contactor is de-energized, which suspends compressor operation. The control will go into soft lockout mode initializing a three minute time delay and a random start of 3 to 10 sec- ond time delays. Once these delays have expired, the unit

will be allowed to run. If a high pressure situa- tion occurs within one hour of the first situa- tion, the control will be placed into a manual lockout mode, halting compressor operation, and initiating the gener- al alarm.

In a low temperature situation, the low pres- sure switch will transi- tion open after the com- pressor starts. If the

switch is open for 45 seconds during compressor start, the unit will go into soft lockout mode initializing a three minute time delay and a random start of 3 to 10 second time delays. Once these delays have expired, the unit will be allowed to run. If the low pressure situation occurs again within 30 min- utes, and the device is open for more than 45 seconds, the control will be placed into a manual lockout mode, halting compressor operation, and initi- ating the general alarm.

In a condensate overflow situation, the control will go into manual lockout mode, halting compressor operation, and initiating the general alarm.

The general alarm is initiated when the control goes into a manual lockout mode for either high pressure, low pressure or condensate overflow condi- tions.

Diagnostics

Component device connections to the microprocessor board are referenced in Figure 25. Three LEDs (light emitting diodes) are provided for indicating the operating mode of the controller. See the unit IOM for diagnostics or trou- bleshooting through the use of the LEDs.

Figure 25: Deluxe 24V control board.

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