Condenser Control; Air Cooled Condensers; Air Cooled Strategy; Temperature Differential Strategy - Emerson E2 Installation And Operation Manual

LIQUID RECEIVER
CIRCUIT
CASE TEMP
(FOR FLOATING)
LIQUID LINE
SOLENOID
SUCTION
PRESSURE
OIL
PRESSURE
Figure 11-1
- Diagram of a Suction Group
Wire Output
Output Device Board Contacts
Compressor N.C.
Unloader N.C.
Liquid Line Sole- N.C.
noid (LLS)
Electric Defrost N.O.
Table 11-2
- Suction Group Outputs

11.2 Condenser Control

An E2 RX is capable of controlling air-cooled or evap-
orative condensers. The E2 RX-300 may control a single
condenser, while the RX-400 may control up to two con-
densers.

11.2.1 Air Cooled Condensers

An air-cooled condenser consists of one or more fans
that blow air across a manifold of tubing to cool heated
refrigerant and condense it into a liquid. The E2 controls
condensers by activating or deactivating fans in order to
maintain discharge pressure or temperature at or below a
chosen setpoint.
A Condenser Control application may use either of two
strategies to operate air cooled condensers: an air-cooled
strategy, or a temperature differential (T-D) strategy.
11.2.1.1

Air Cooled Strategy

The air cooled strategy uses a simple PID control loop
Condenser Control
DISCHARGE
PRESSURE
OIL RESET SWITCHES
D D D
26507005
Set Failsafe Dip
Switch to:
to:
N.C. (up)
N.O. (down)
N.C. (up)
N.O. (down)
Input Sensor Type
Suction Pressure 100 lb. Eclipse
transducer
Discharge Pres- 500 lb. Eclipse
sure transducer
Oil Pressure 200 lb. Eclipse
transducer
Case Circuit Temperature
Temperature
Oil Reset Digital
Switches
Table 11-1
- Suction Group Inputs
Notes
If you want a compressor to be OFF during network/power loss,
use N.O. failsafes instead.
These fail-safe settings are specifically for unloaders.
Keeps solenoid energized during network/power loss.
Keeps contacts de-energized during network/power loss.
that compares a single Control In input to a PID setpoint.
The resulting percentage is used to activate the condenser
fan(s) necessary to bring the input value down below the
setpoint.
Control inputs for air cooled strategies most commonly
come from a pressure transducer mounted on either the
discharge line, the condenser inlet, or the condenser outlet.
However, temperature sensor values will also be accepted.
11.2.1.2 Temperature Differential Strat-
egy
The temperature differential strategy attempts to keep
a minimum amount of difference between the temperature
of the refrigerant and the ambient outside temperature.
This strategy begins by determining the temperature of
the refrigerant coming into the condenser. This can be sup-
plied by either a temperature sensor or pressure transducer
located near the condenser inlet; if it's a pressure trans-
ducer, its value will automatically be converted to a tem-
perature value based upon the type of refrigerant.
Wiring
Instructions
see Table 9-1 on
page 9-3.
see Table 9-1 on
page 9-3
see Table 9-1 on
page 9-3
see Table 9-1 on
page 9-3
see Table 9-1 on
page 9-3
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Software Overview 11 3