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Condenser
Control
The EPC-2000 can operate a remote
condenser with up to seven independent
fan banks and one split condenser valve.
The EPC-2000 can monitor the head
pressure, ambient temperature, liquid
drop leg temperature, a gas defrost
status signal, and a heat reclaim status
signal.
Sequential Staging--The
EPC-2000 will sequentially stage
the fan banks in the FILO format
(first on last off). The fan bank
closest to the condenser input
manifold should always be
assigned as the first, or
primary, fan bank. The EPC will
keep the first fan bank running
nearly constantly to prevent
expansion and contraction at the
pipe and tube sheet joints.
Parallel Fan Bank
Control--If the
condenser has a primary side and
a secondary, or split, side with
fans on each side, both sets of
fans should be controlled by the
same condenser relay. The
contactor power for the split
fans should also be controlled by
the Split Condenser Relay on the
EPC Condenser Board.
Fixed Head Pressure
Control--The EPC-2000
can stage the condenser fan banks
based upon a fixed head pressure setpoint.
Floating Head
Pressure Control--The
EPC-2000 can stage the condenser fan
banks based upon the temperature of
the liquid drop leg temperature and
ambient temperature. The EPC-2000
will maintain the liquid at the
Ambient Sub Cooled Refrigerant Setpoint.
Split Condenser--The
EPC-2000 will attempt to maintain
the condenser in its smallest
configuration. If the EPC-2000
can maintain the head pressure
while in the "split
condenser" mode even though
the ambient temperature is above
70 °F, the EPC will do so. The
EPC-2000 will lock into the Split
mode when the ambient temperature
is below a setable ambient
temperature Setpoint. The EPC
will only come out of split
condenser when the following
occurs:
-
The head pressure reaches 85%
of the high head pressure
alarm level.
-
The maximum number of fan
banks are operating and the
head pressure continues to
rise.
When the EPC-2000 goes into Split
Condenser, the EPC closes the
Split Condenser Relay, closing
the split valve and shutting
power off to the split side fans,
and will automatically double the
number of fan banks previously
being run. When the EPC-2000
comes out of Split, the Split
relay will open, and the number
of fan banks being run will be
halved.
Ambient Temperature
Compensation of the Fan
Start/Stop Timing--The
EPC will adjust the start and
stop timing of the condenser fans based upon the ambient
temperature. The EPC will more
than likely start fans faster
when the ambient temperature is
warmer and will stop fans faster
when the ambient temperature is
cooler.
Minimum Head Pressure
During Heat Reclaim--When
the EPC-2000 detects the Heat
Reclaim relay is energized, the
EPC will maintain a minimum head
pressure by reducing the number
of fan banks active and adjusting
the compressor staging.
Minimum Head Pressure
During Gas Defrost--The
EPC-2000 will maintain a minimum
head pressure by reducing the
number of fan banks active and
slowing the compressor staging.
Fan Staging After Gas
Defrost--The EPC-2000
will adjust the fan control
algorithm immediately following
the end of a gas defrost. The EPC
will anticipate the increase of
load due to the recovery time of
the defrost circuit.
Parallel Mechanical
Backups--Backup pressure
controllers or thermostats are
wired in parallel with the EPC
Condenser Control Relays with
their power supply circuitry wired
through the Condenser Switchback
Relay. If the EPC were to fail,
the Condenser Switchback Relay
will de-energize, supplying power
to the backup controls. The
backup controls may be set as
closely to the Head Pressure Setpoint as possible.
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