|
Features
Control of a Parallel Rack
with One Suction Group
The EPC-1000 Multiplex Refrigeration
Control System is an all electronic, Y2K
compliant control system that can control
the compressors, condenser and defrost of
a multiplex refrigeration rack.
Easy to Use--The
EPC-1000 is operated entirely by the
front control panel. The system is
menu-driven, and the four button keypad
allows the user to make changes quickly
by answering the prompted questions. Data
is shown on a 1 by 10 character display. The alarm log retains the last 5
alarm conditions, including the time,
date and cause of each alarm.
Adjusts to Operating
Conditions--The EPC-1000 uses
"Heuristics" to continuously
analyze refrigeration performance and
modify the operation of the compressors
and unloaders to maintain a stable
suction pressure. Stable suction pressure
optimizes case efficiency.
Operating Parameters--All
pressure operating parameters, such as
Suction Pressure Setpoint, are single
value settings. No Cut In Cut Out values
or staging levels are required. Once the
operating level is entered, the EPC-1000
will stage the compressors and unloaders
in their most efficient mode to maintain
the operating pressures.
Prolongs Compressor Life--The
EPC-1000 continuously monitors suction
pressure and compressor runtimes and
turns the compressors on and off
automatically to ensure balanced
operation of the compressors. Harmful
compressor short cycling is eliminated.
Memory Protection--The
EPC-1000 uses the latest EEPROM and
static RAM technology to store
configuration data, operational settings,
and the alarm log. A power outage will
not alter or erase any stored data. The
system clock is battery backed and will
retain the time and date for up to 5
years without power. The clock is Y2K
compliant and leap year compliant until
year 2100.
GenCom Communications
Capability--With a MS-DOS or
Windows operating system based computer
and a modem, a user can monitor and
control several EPC-1000 units from
within a store or from a remote location.
This option provides full accessibility
to the EPC-1000's functions and keeps the
user aware of system alarm and operating
conditions.
COMPRESSOR CONTROL
Compressors--The
EPC-1000 is capable of controlling a rack
with up to six parallel fixed-speed
compressors or a combination of
compressors, unloaders, and satellites up
to a total of six. The parallel
compressors will be activated based upon
the suction pressure setpoints with a
heuristic algorithm.
Staging--The
compressor staging method can be set for
sequential staging, random (round-robin)
staging, a combination of sequential and
round-robin, or by custom staging steps
programmed by the user via a mix match
table.
-
Sequential--The
compressors will be activated and
deactivated in a FILO format, the
first compressor on will be the
last compressor turned off.
-
Round-Robin--The
compressors will be activated and
deactivated randomly in order to
maintain even compressor run
times over a 24 hour period. Each
compressor will be activated at
least once every two hours to
prevent the lubrication oil from
migrating out of the compressor.
-
Combination of Sequential
and Round-Robin--For
parallel racks with two different sizes of compressors or one
compressor with an unloader. It will
activate the sequential
compressors via the FILO format,
then it will activate the
round-robin compressors randomly.
The sequential compressors will
be de-activated last.
-
Mix Match--On
parallel racks with different
compressor sizes. The user sets
the order of which the
compressors will activate and
de-activate in order to smooth
the rack operating step sizes.
Unloaders--Each
unloader can be assigned to any of the
parallel compressors. The unloaders will
operated on an accelerated algorithm as
compared to the compressor algorithm.
When a compressor with an assigned
unloader is activated, the compressor
will initially start unloaded. If the
EPC-1000 requires an increase in the
rack load, the compressor will then
be fully loaded before an additional
compressor is activated.
Compressor Swing Staging--When
the rack is set up to run in a
combination of sequential and round-robin
mode, the first sequential compressor
will operate as the swing compressor.
This compressor, usually a smaller
compressor, will be activated prior to
the activation of one of the round-robin
(bigger) compressors. The smaller
compressor will act as a half step,
smoothing out the performance of the
rack.
Mechanical Back-Up--Mechanical
pressure controls can be installed on the
rack and operate in two different
methods:
-
Series Switchback--The
EPC-1000 is configured to operate
the compressors by de-energizing
the control relays. The
mechanical low pressure controls
are wired in series with the
EPC-1000 control relays. If the
control fails, all compressor
relays will be activated and the
low pressure mechanical
controllers will cut out the
compressors when the suction goes
below their settings. NOTE:
This method is only possible with
the addition of a timing relay in
series with the compressor
contactor coil voltage to prevent
short cycling on start-up.
-
Parallel Switchback--The
EPC-1000 is configured to operate
the compressors by energizing the
control relays. The mechanical
low and high pressure controls
are wired in parallel to the
EPC-1000 with the line voltage to
the backup wire through an
de-energized
"Switchback" time delay
relay. If the EPC fails, all EPC
control relays are de-energized,
the Switchback relay is energized
and power is switched to the
backups. The mechanical backup
controls now operate the
compressors based upon their
Cut-IN and Cut-Out settings. With
this method, the backup settings
can be set to run the rack as
closely to the suction setpoint
as possible.
Defrost Recovery--The
Compressor Heuristic Algorithm will
accelerate the staging of the compressors
immediately following the termination of
a gas defrost circuit.
|
