Emerson VE, VH, DE, DH manual Select Control Type, Setup Alarms

Advanced Microprocessor Controls Setup

Dehumidification with Normal or Delayed Reheat: Dehumidification with normal reheat allows for operating BOTH compressors and reheats simultaneously. It is very important that electrical ser- vice to the unit be sized and wired for this option if selected.

! CAUTION

If the electrical service to the unit is not properly sized for this option, it could trip the building circuit breakers (or fuses) or, in extreme cases, damage the building wiring.

With delayed reheat selected, the reheats are prevented from turning on when dehumidifying with both compressors until the point at which 100% heating is called for. At this time, the compressors are turned off until the reheats bring the temperature back up to the point at which the reheats are turned off.

Select Control Type

•INTELLIGENT

•PROPORTIONAL

•TUNABLE PID

The type of system control method used by the microprocessor can be selected from the front panel. The default setting is INTELLIGENT, which approximates the actions that a human operator would take to maintain precise, stable control. The control logic uses Artificial Intelligence techniques including “fuzzy logic” and “expert systems” methods to maintain precise, stable control and increase reliability by reducing component cycles. PROPORTIONAL is a standard control method that uses one gain factor (temperature sensitivity adjustment). TUNABLE PID (Proportional, Integral, and Derivative) uses three gain factors selected by the operator. PID allows precision tuning, but requires an experienced operator and seasonal adjustments. Note that if PID is selected, it is used for temper- ature control while humidity will continue to use Proportional Control. For chilled water units with the optional Variable Speed Drive, Intelligent Control is required for proper operation.

Refer to 5.0 - Response by Control Type—Advanced Microprocessor Controls for more detail on types of control.

Setup Alarms

Selecting SETUP ALARMS will step to the following menu:

•SET TIME DELAYS

•ENABLE ALARMS

•ENABLE COMMON ALARM

•SET CUSTOM ALARMS

Each individual alarm can be programmed with a time delay from 0 to 255 seconds. Each individual alarm can be ENABLED or DISABLED and each individual alarm can be programmed to energize or not to energize the Common Alarm Relay.

Set Time Delays: By programming a time delay for an alarm, the system will delay the specified amount of time before recognizing the alarm. The alarm condition must be present for the amount of time programmed for that alarm before it will be annunciated. If the alarm condition goes away before the time delay has timed out, the alarm will not be recognized and the time delay timer will be reset. For software alarms such as Loss of Power, Short Cycle, and Low Suction Pressure, a time delay will only delay the annunciation of that alarm. The condition of the alarm is not applicable because the condition has already occurred. For these alarms the time delay should be left at the fac- tory default of 0. The following table shows the default time delays for each alarm.

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