©2025 Copeland LP.
026-1803 R13 Supervisor I&O User Guide 9 - 53
The user supplies Temperature Control with the setpoint and
a deadband, which is the range of case temperatures equally
above and below the setpoint within which the case
temperature will be considered acceptable. When the case
temperature is above the setpoint plus
one-half the
deadband, refrigeration will be turned ON. It will remain ON
until the temperature drops to below the temperature
setpoint minus
one-half the deadband, at which point
refrigerant flow will be turned OFF.
Case temperature may be supplied to Temperature Control
by a supply air sensor, a return air sensor, or a mixture of both
the supply and return air sensor values.
Temperature Control itself does not vary the opening
percentage of the pulse or stepper valve; it simply addresses
the case’s need for refrigerant flow to maintain its setpoint.
Once refrigeration is started, control of the valve is handled by
Superheat Control.
Superheat Control
The difference between the temperature of the refrigerant
going in to the evaporator inlet (the coil in temperature) and
the refrigerant leaving the evaporator outlet (the coil out
temperature) is called Superheat. When refrigerant is flowing
through an evaporator, Superheat Control uses PID Control to
keep the Superheat at a user-defined Superheat setpoint.
Superheat Control positions the valve to increase or decrease
refrigerant flow in an effort to keep the Superheat equal to a
user-defined Superheat setpoint.
Recovery Mode
Recovery Mode is a special part of Superheat Control that
occurs at the beginning of every refrigeration cycle. When
refrigeration has been OFF and Temperature Control calls for
refrigeration to be ON, a Recovery Mode begins, during which
the valve is fixed to a user-defined percentage (usually 70%)
for a fixed amount of time. This floods the previously empty
evaporator with refrigerant and gradually establishes a
differential between the coil in and coil out temperatures.
When the Recovery Mode ends, the superheat will be
relatively close to the setpoint; at this time, Superheat Control
will begin.
Recovery Mode always lasts for a specific number of
seconds. The case controller determines the duration based
on past performance of the evaporator during previous
Recovery Modes.
Thermostatic Expansion Valves (TXVs)
As an alternative to regulating superheat using EEVs, case
controllers also support cases that use mechanical
thermostatic expansion valves (TXVs). When TXVs are being
used, the case controllers use only Temperature Control to
turn refrigeration ON and OFF. Superheat Control is disabled,
since it is assumed the TXV is taking care of the superheat.
9.38.3.2 EEPRs (Suction Stepper)
The CC-100H, CS-100, and CCB (suction stepper and lineup)
control case temperature from the suction side of the
evaporator by using an EEPR to regulate suction pressure.
Suction-side control differs from liquid-side control in that
Superheat Control is not used. In liquid-side control, the valve
aperture is controlled in order to achieve a superheat
setpoint. In suction-side control, the CC-100 changes the
valve aperture to achieve the case temperature setpoint.
Case temperature may be supplied by a supply air sensor,
return air sensor, or a mixture of the two values.
Temperature Control uses PID control to operate the valve
and keep the case temperature input value equal to the case
temperature setpoint.
Recovery Mode
Recovery Mode for suction-side case controllers is slightly
different than Recovery Mode for liquid-side controllers.
Suction-side case controllers enter Recovery Mode only after
a defrost or cleaning cycle, and it does so in order to bring the
case temperature down to a level that is controllable by
Temperature Control.
During Recovery Mode, the valve is opened to a fixed
percentage until the case temperature falls below the case
setpoint. When this occurs, the case controller exits Recovery
Mode and begins normal Temperature Control.
9.38.4 Defrost Control
The physical aspects of defrost control, such as shutting off
valves and turning on defrost heat sources, is handled by the
case controller. When operating on its own, a case controller
initiates defrost cycles at programmed time intervals. When
connected to a Case Circuit application, the case controllers’
defrost times are coordinated and scheduled by the
Supervisory Controller.
9.38.4.1 Defrost States
The defrost cycle for a Case Circuit application consists of
three steps. Of these three, steps #1 and #3 apply only to
cases with heated defrosts:
1. Pump Down - The defrost cycle begins with this step
immediately after the refrigeration solenoid is turned OFF.
During the Pump Down phase, the application waits for a
user-specific amount of time to elapse before turning on
the defrost heat. This allows refrigerant in the evaporator
to be evacuated before defrost heat is activated. The
compressor(s) remain ON during Pump Down. Pump
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