Bard MC4000 Alarm Wiring, 2ND STAGE COOLING ALARM, Refrigerant Pressure Alarms

ALARM WIRING

Alarm relays can be wired for NO (close on alarm) or NC (open on alarm) strategy.

Alarm relays can be used individually if there are enough available building alarm points, or can be arranged into smaller groups or even a single group so that all alarm capabilities can be utilized.

When multiple alarms are grouped together and issued as a single alarm, there will no off-site indication of which specific problem may have occurred, only that one of the alarms in the group has been triggered. The individual alarm problem will be shown on the LED display on the face of the controller.

Note: All alarm and output relays are Form C (SPDT) dry contacts rated 1A @ 24 VAC.

Note: All alarm relay outputs have 10-second delay in acutally issuing to protect against nuisance alarm signals.

The Power Loss 1, Power Loss 2 and controller alarm relays are all “reverse actuated”, which means they are continuously energized (the NO contact is closed) and switched to NC position upon alarm condition.

Therefore, it is important to closely follow the alarm board connection diagrams that follow.

Any alarm feature that is not desired can simply be ignored (not connected).

NOTE: The alarm LED display board is shipped uninstalled to protect it from possible damage during installation of the wiring to main controller board and/or the alarm board. It is polarity sensitive and is keyed so it can only be installed in correct position.

NOTE: The LED display board can be replaced if needed independently of the alarm board. Bard part number is 8612-022.

ALARM LED DISPLAY BOARD

MIS-2042

2ND STAGE COOLING ALARM

This alarm output is available for use if desired. It is important to note that in some installations, due to A/C system sizing and internal heat load, that the secondary (lag) air conditioning unit may be called upon to assist the lead air conditioner some of the time. If this is the case, or possibly when additional heat load is added, using the 2nd stage cooling alarm will cause nuisance alarm conditions.

Note: For units with 2-stage compressors, the dual stage cooling alarm activates on cooling Stage 3 initiation. Menu Step 23, CoPr, must be set to “2” for this to occur, otherwise alarm will activate on cooling call Stage 2 causing nuisance alarm.

For installations where it is known that there is 100% redundancy (one air conditioning unit can handle 100% of the load 100% of the time) use of the 2nd Stage Cooling Alarm is a method to issue an alarm signal that the lead air conditioner is down (or not delivering full capacity) and that the lag air conditioner is now operating.

REFRIGERANT PRESSURE ALARMS

Air conditioners with “J” control module are equipped with an alarm relay that is activated upon high or low refrigerant pressure lockout conditions. Connecting terminals 2 and 3 from the air conditioner 24V terminal block to the matching terminals 2 and 3 on the alarm board will allow these alarms to function.

EMERGENCY VENTILATION SEQUENCE

For units with economizers, there are two (2) emergency ventilation sequences designed into the controller. Both require the -B alarm board and connection of terminals E and F from the air conditioner 24V terminal block to the matching terminals on the alarm board.

Note: The E and F wiring connections at the 24V terminal block in the A/C units are different for older style EIFM economizers than for newer style ECONWMT economizers. Refer to the appropriate Controller Connection diagrams - See Table 1.

Sequence one requires a refrigerant pressure alarm, coupled with high temperature alarm condition No. 1 (HAL 1 set point). If both of these conditions occur, the economizer in the air conditioner that issued the refrigerant alarm will drive open to ventilate the building.

Sequence two (HAL 2 set point) is activated by high temperature alarm No. 2, and will initiate even without a refrigerant pressure alarm signal. Both economizers will be activated to provide emergency ventilation. This strategy help protect against building overheating if air conditioner(s) are inoperative for non-pressure related reasons (bad compressor, contactor, run capacitor, etc.).

NOTE: The LED display board is polarized and will only fit in one direction as shown. It must be fully inserted in order for the controller to function properly.

Manual	2100-563C
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