Operating manual
Document nr. : 022091
Version : V2.3
MC 785-SC
Client : General
Page : 7 of 32
The SUCTION part (compressor-side):
Readout selection on the SUCTION display.
By pressing the left
SELECT
key next to the SUCTION display once or more, the following
values can be shown on the display:
S
The suction pressure in Bars, LED Bar next to the display lights up.
S
The calculated suction temperature (depends on coolant) in degrees Celsius, LED’s
Bar and
O
C light up.
S
The suction temperature, of temperature sensor-1, in degrees Celsius, LED
O
C lights
up.
S
The operation hours of one of the compressors, to select another compressor, press
the left
UP
or
DOWN
keys. To show which compressor has been selected for readout,
the corresponding LED in the compressor bar will light up and the LED Hrs. will light
up.
S
Current control signal in percentage, LED % lights up.
Further, there are two more LEDs (
and
) in the SUCTION display panel, these LED’s
indicate if the control signal is increasing or decreasing the compressor power.
Showing status of the compressors.
In the COMPRESSOR panel the status of the compressors is shown in different ways which
can be selected by the left
MODE/SELECT
key. These readout modes are;
S
Normally the LED’s Service and Fail will not be lit, then the LED bars indicate:
Upper LED bar shows which compressors are active.
Lower LED bar shows which compressors are running in time delay.
Or
S
LEDs Service and Fail are lit, then the LED bars indicate:
Upper LED bar shows which compressor is in service.
(These compressor(s) will not be selected for controlling by the controller).
Lower LED bar shows which compressor is in failure.
Readout or changing the suction pressure (/temperature) setpoint.
By pressing the left
SET
key, the suction pressure setpoint is shown in the SUCTION display.
To indicate this the Bar lights up. By pressing the left
SELECT
key, the setpoint will be shown
in degrees Celsius (also adjustable), LEDs Bar and
O
C light up.
To change the setpoint value now press the left
UP
or
DOWN
keys. 10 seconds after the keys
have been released the new setpoint will be active and the controller will return to its normal
display function again. Notice that the controller calculates the temperature signals to pressure
signals and controls on the pressure signals.
Setting a compressor in or out of service.
To put a particular compressor out of function, it must be set in service.
To see which compressors are in service press the
PRG
key together with the left
MODE/SELECT
key. The LED Service will light up and the LED bars show:
Upper LED bar shows which compressors are in service and
Lower LED bar shows the currently-selected compressor.
With the left
UP
and
DOWN
keys another compressor can be selected. The compressor to be
put in or out service can be put in or out of service by pressing the left
MODE/SELECT
key.
Resetting operation hours of a particular compressor.
Read out the operation hours on the SUCTION-display by pressing the left
SELECT
key once
or more, until the LED Hrs lights up. Then select the compressor which has to be set to zero
with the left
UP
and/or
DOWN
keys. Now press the
RESET/ALARM
key, hold it down and
press simultaneously on the left
MODE/SELECT
key to set the selected compressor operation
hours to zero.
