Daikin RDT Installation And Maintenance Manual page 74

Differential Enthalpy Control (OAE/RAE)
An optional electric differential enthalpy control arrangement
(OAE/RAE) is available on units with MicroTech III control.
In this configuration a solid-state humidity and temperature
sensing device is located in both the return (RAE) and outside
intake (OAE) airstreams. This OAE device has the same A
through D scale as the device described above. However, with
the OAE/RAE arrangement the switch on, OAE must be set all
the way past the D setting. With this done, the MicroTech III
controller adjusts the return and outside air dampers to use the
airstream with the lowest enthalpy.
IM 893-10 • ROOFPAK SINGLEZONE UNITS
Ground Fault Protection
The ground fault protection is designed to protect motors
from destructive arcing ground faults. The system consists of
a ground fault relay and a ground fault current sensor. The
ground fault relay employs solid state circuits that will instantly
trip and open a set of relay contacts in the 115-volt control
circuit to shut the unit down whenever a ground fault condition
exists. The ground fault relay is self powered. The ground fault
sensor is a current transformer type of device located on the
load side of the power block through which the power wires of
all phases are run.
Phase Voltage Monitor
The phase voltage monitor (see
high voltage, phase imbalance, and phase loss (single
phasing) when any one of three line voltages drops to 74% or
less of setting. This device also protects against phase reversal
when improper phase sequence is applied to equipment, and
low voltage (brownout) when all three line voltages drop to
90% or less of setting. An indicator run light is ON when all
phase voltages are within specified limits. The phase voltage
monitor is located on the load side of the power block with
a set of contacts wired to the 115-volt control circuit to shut
the unit down whenever the phase voltages are outside the
specified limits.
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