EWWQ090G ÷ EWWQ720L - R410a - Water-cooled scroll chillers
EWLQ090G ÷ EWLQ720L - R410a - Condenser less
EWHQ100G ÷ EWHQ400G - R410a - Heat pump scroll chillers
Water cooled scroll chillers & heat pump
Operation
Manual
EWWQ - EWLQ - EWHQ
Water cooled scroll chiller &heat
pump
D-EOMWC01203-15EN
Operation Manual
7
In the event of a power supply outage, the unit will restart automatically without the need for an
external command. However, any faults active when the supply is interrupted are saved and
may in certain cases prevent a circuit or unit from restarting.
Direct intervention on the power supply can cause electrocution, burns or even death. This action
must be performed only by trained persons.
Flowswitch
The unit must be protected by a flowswitch. The flowswitch will stop the unit when the water
flow becomes lower than the minimum allowed flow. When the water flow is restored the flow
protection resets automatically. Exception is when the flowswitch opens with at least one
compressor running, in this case the alarm shall be cleared manually.
Freezing protection
Antifreeze protection prevents the water to freeze in the evaporator. It is automatically activated
when the water temperature (entering or leaving) at the evaporator drops below the antifreeze
limit. In freeze condition if the unit is in standby the evaporator pump will be activated to prevent
freezing of the evaporator. If the freeze condition will activate when the unit is running all the
unit will shut down in alarm while the pump will keep running. Alarm will automatically clear
when the freeze condition will clear.
Low pressure protection
If the circuit operates with a suction pressure lower than an adjustable limit for a certain time the
circuit safety logic will shut down the circuit and generate an alarm. The alarm requires a
manual action on the Unit Controller to be reset. Reset will take effect only if the suction
pressure is no longer lower that the safety limit.
High Pressure Protection
If the discharge pressure becomes too high and exceeds a limit which is linked with the
operational envelop of the compressor the circuit safety logic will try to prevent the alarm or, if
the corrective actions have no effect, it will shut down the circuit before the Mechanical High
Pressure switch will open. This alarm required a manual action on the Unit Controller to be
reset.
Mechanical High Pressure Switch
Each circuit is equipped with at least one high pressure switch which tries to prevent the relief
safety valve to open. When the discharge pressure becomes too high the Mechanical High
Pressure switch will open and immediately stop the compressor cutting the power supply to the
auxiliary relay. The alarm can be cleared as soon as the discharge pressure becomes normal
again. The alarm must be reset on the switch itself and on the Unit Controller. The triggering
pressure value cannot be changed.
Relief Safety Valve