EWWQ090G ÷ EWWQ720L - R410A - Water-cooled scroll chillers
EWLQ090G ÷ EWLQ720L - R410A - Condenser less
EWHQ100G ÷ EWHQ400G - R410A - Heat pump scroll chillers
EWAQ-
- R410A - Air-cooled scroll chillers
EWAQ-
- R410A - Air-cooled scroll chillers
EWYQ-
- R410A - Air-cooled scroll heat pumps
Air and Water cooled scroll chillers & heat pump
Operation
Manual
EWWQ - EWLQ - EWHQ
EWAQ - EWYQ
Air or Water cooled scroll chiller &
heat pump
D-EOMHW00107-15EN
Operation Manual
7
1.3 Safety Devices
Each unit is equipped with safety devices of three different kinds:
1.3.1 General safety devices
Safeties of this level of severity will shut down all the circuits and stop the entire unit. When a
general safety device will occur a manual intervention on the unit will be required in order to re-
establish the normal operability of the machine. There are exceptions to this general rule in case of
alarms linked to temporary abnormal conditions.
Emergency Stop
A push button is placed on a door of the unit electrical panel. The button is highlighted by a red
color in yellow background. A manual pressure of the emergency stop button stops all loads from
rotating, thus preventing any accident which may occur. An alarm is also generated by the Unit
Controller. Releasing the emergency stop button enables the unit, which may be restarted only
after the alarm has been cleared on the controller.
The emergency stop causes all motors to stop, but does not switch off power to the unit. Do not
service or operate on the unit without having switched off the main switch.
1.3.2 Circuit safety devices
Safety of this level of severity will shut down the circuit they protect. The remaining circuits will
keep running.
1.3.3 Component safety devices
Safety of this level of severity will shut down a component against abnormal running condition that
could create permanent damages to it. An overview of the protecting devices is listed below:
Overcurrent/Overload Protections
Overcurrent/overload devices protect electrical motors used on compressors, and pumps in
case of overload or short circuit. In case of inverter-driven motors, overload and overcurrent
protection is integrated in the electronic drives. A further protection from short circuit is
accomplished by fuses or circuit breakers installed upstream each load or group of loads.
Overtemperature Protections
Compressors are also protected from overheating by thermistors immersed into motor windings.
Should the winding temperature exceed a fixed threshold, the thermistors will trip and cause the
motor to stop.
Phase reversal, under/over voltage, ground fault protections
When one of those alarms occurs the unit is immediately stopped or even inhibited to start. The
alarms clear automatically once the problem is fixed. This auto clear logic allows the unit to
automatically recover in case of temporary conditions where the supply voltage reaches the
upper or lower limit set on the protection device. In the other two cases a manual intervention
