A—MR4PMUHV Electronic Temperature/Defrost Control with Relay Pack Product/Technical Bulletin 9
0 disables the defrost cycle in both manual and
automatic modes.
G&
Dripping time: After defrost is terminated, the
compressor is stopped for this length of time to
allow the evaporator to drip.
G8
First defrost after power-on: This parameter
delays the first defrost cycle after powerup. The
control will not initiate a defrost cycle for the
length of time set in this parameter. It can be
used to allow the system to reach operating
temperature before the defrost cycle is initiated.
Setting this parameter to
2)
(Off) disables the
first defrost after power-on. Normally, the first
defrost occurs after the
GL
interval has elapsed.
G3
Display during defrost: Selects what
temperature is displayed during a defrost cycle:
0 = Last measured value before defrost cycle
1 = Setpoint
GU
Display delay after defrost: During defrost
cycles, the ambient temperature is not displayed
(see parameter
G3
). The actual temperature is
displayed when it reaches the setpoint value or
after the time defined by this parameter.
L)
Digital input function: The digital input (normally
closed) can be configured according to
installation requirements:
0 = The digital input is not connected
1 = If the contact is open for a time longer than
that set through parameter
LG
, the
compressor, defrost, and fan outputs are
switched Off, an alarm message (A1) is
displayed, and the alarm output is switched
On.
2 = Alarm function: If the contact is open for a
time longer than that set through parameter
LG
, an alarm message (A2) is displayed and
the alarm output is switched On.
3 = Open door alarm: When the contact is open,
the fan is switched Off. If the contact is open
for longer than the time set through
parameter
LG
, an alarm message (A3) is
displayed, the alarm output is switched On,
and high and low temperature alarms are
disabled.
LG
Digital input time delay: This is the time
between the detection of the digital input
opening and the enabling of the function
selected through parameter
L)
.
))
Fan operating function:
0 = Fan runs when the compressor runs
1 = Fan is always On
Note: The fan is always switched Off during
the defrost cycle.
)G
Fan start-up delay (after defrost): The fan is
activated after this time even if the temperature
set through parameter
)U
has not been reached.
)U
Fan start temperature after defrost end: This is
the evaporator sensor temperature at which the
fan is switched On after a defrost cycle.
Note: If the start temperature is not reached,
the fan is switched On after the time set
in parameter
)G
.
6)
Sensor failure operation: This parameter
defines how the control functions after a
temperature sensor failure:
0 = Compressor remains On
1 = Compressor remains Off
2 = Automatic:
In automatic mode, the controller calculates the
average time the compressor was On during the
last four cycles. The controller then cycles based
on the average of these cycles. If a deep freezing
cycle or a defrost cycle occurred in the last four
cycles, they will not be taken into account nor will
the first cycle after the deep freeze or defrost.
6R
Temperature sensor offset: This value is added
to or subtracted from the measured value to
compensate for possible field measurement
offset errors. To compensate for extra long
copper cabling use the following table:
Table 2: Wire Size and Cable Length
Wire Size and Cable Length
18 AWG 20 AWG 22AWG Offset
300-599 ft 190-374 ft 120-239 ft 1F°
600-899 ft 375-564 ft 240-349 ft 2F°
900+ ft 565+ ft 350+ ft 3F°
8Q
Temperature units used: Determines
temperature units used for parameter settings.
0 = Celsius degrees
1 = Fahrenheit degrees
38
Display refresh rate: The temperature display is
refreshed at this rate. The display refresh rate
does not affect control performance.
