Hydraulic module control
23
RLC-SVU02F-E4
Control logic
Turning the control on
When switching on, all the outputs
will be disabled.
Reaction in case of failure
• Failure on entering water
temperature sensor (EWT):
A failure on this sensor (value out
of range) will disable the return
water temperature control during
the freeze protection by pump
activation.
• Failure on ambient Air temperature
sensor (OAT):
A failure on this sensor (Value out
of range) will turn on the heater
output and enable the freeze
protection by pump activation.
• No water flow while pump is
activated (demanded) or WFP:
If the water flow input is open (no
flow) for more than 20s while
pump is demanded for cooling or
for freeze protection by pump
activation, then an automatic
latching alarm is activated. During
the 10 first seconds of this flow
alarm, the module will switch to
the backup pump to try to obtain a
water flow.
• Water flow without pump
activation (demand):
If the water flow input is closed
(flow detected) for more than 30s
without pump demand and
without manual forced activation,
then an automatic latching alarm
will be activated.
Freeze protection resistance control
This application must control the
electric heater command to protect
the unit during low ambient
temperature when UCM-CLD
doesn't demand pump activation.
Electric Heater ON/OFF
If the ambient air temperature is
lower than the heater activation
setpoint -1°C, then the heater output
is activated. When the ambient
temperature r1°C over the
setpoint, the output is deactivated.
Pump control
This application must control 2
pumps mounted in parallel on the
evaporator circuit of a RTAD unit.
• Pump start and stop
When a pump demand is sent by
the UCM-CLD module and when
the system is enabled, the control
is in charge of the activation of on
the 2 pumps (1 at a time). A
hardware safety exists on the
electrical panel not to start both
pumps at the same time.
• Automatic change-over on a pump
failure:
When a failure appears on a pump
in operation, the control will
automatically switch on the other
pump and will stop the faulty
pump.
• Automatic change-over on failure
on water flow:
When a water flow loss is detected,
the control will automatically
switch on the backup pump to try
to keep water flow in the loop. If
the alarm remains or if the second
pump is out of order, an auto
latching alarm is triggered.
• Pump change-over on pump start:
When a new demand to start a
pump appears, a pump change-
over will be done on the pump to
preserve pump mechanical seals.
• Freeze protection by pump
activation:
When UCM-CLD does not require
pump activation and that ambient
temperature is lower than the
electric heater freeze protection
setpoint but over 0°C, then a
water pump is cyclically activated
(5 min ON, 10 min OFF
programmable). If the ambient
temperature is lower than 0°C,
the pump is operating
continuously. This protection may
be deactivated.
However, if the ambient air
temperature is lower than the low
ambient setpoint (as a default
-18°C), the freeze protection by
pump activation is reactivated.
In all cases, a temperature control
on the return water temperature
will limit the water temperature of
the loop. If this temperature goes
over +15°C (programmable)
during 5mn, then the pump is
stopped during 10mn
(programmable) and then will
cycle according to these timers.
