119
JOHNSON CONTROLS
FORM NO.: 6U6K-B01E-NB-EN
If the sensor has to be repositioned it should remain in contact
with the coil capillary and be placed adjacent to the coil end
plate which indicates the frost situations of the coils.
ANTI-RECYCLE TIMER
The anti-recycle timer assures that systems do not cycle. This
timer is set to 180 seconds to reduce cycling and motor heating.
The anti-recycle timer starts the timer when the either of the
compressors in a system starts. The timer begins to count down
and the corresponding compressor will not be permitted to start
until the anti-recycle timer has timed out.
ANTI-COINCIDENCE TIMER
This timer is present in software to assure compressors within a
circuit or between systems do not start simultaneously. The anti-
coincidence timer assures there is at least a 40 seconds delay
between compressor loadings. This timer is programmable from
20 to 120 seconds. The load timers further assure that there is
a minimum time between compressor starts within a control
network.
EVAPORATOR AND PIPING HEATER CONTROLS
The evaporator and piping heaters are controlled by ambient air
temperature. When the ambient temperature drops below 3 °C
the heaters are turned on. When the temperature rises above 5
°C the heaters are turned off.
COMPRESSOR CRANKCASE HEATERS
Each compressor is fitted with two crankcase heaters which
will be powered on when ambient temperature drops below
20 °C. The heaters are connected to DO6 of IPU3 through the
terminals.
AUXILIARY HEATER CONTROL
The field-mounted auxiliary heater will be powered on when
ambient temperature is below 5 °C (programmable) and
controlled liquid temperature is 5 °C (programmable) below
setpoint. The output will be cut off when liquid temperature
rises to 5 °C (programmable) below setpoint.
EC FAN CONTROL
Each refrigerant system has one fan installed for forced air
circulation. The micro is responsible for EC fan speed control
by the running parameters.
1.Cooling mode: the fans are controlled by the discharge
pressure;
2.Heating mode: the fans are controlled by the temperature
difference between ambient temperature and saturated suction
temperature;
3.Defrost mode: the fans are off unless the discharge pressure is
above 34 BARG.
ALARM STATUS
System or unit shutdown is indicated by normally-open alarm
contacts opening whenever the unit shuts down on a unit fault,
locks out on a system fault, or experiences a loss of power to
the unit electronics . The alarm contacts are located at XTB2
– terminals 47 to N7. The alarm contacts will close when
conditions allow the unit to operate, or the fault is reset during
a loss of power, the contacts will remain open until power is
reapplied and no fault conditions exist.
SECTION 9 – UNIT OPERATION
Cooke Industries - Phone: +64 9 579 2185 Email: [email protected] Web: www.cookeindustries.co.nz
