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Air and Water cooled inverter chillers and heat pump
D-EOMZC00105-17EN
Operation Manual
8/84
EWAD TZ - EWAD TZ B -EWWD VZ
Air and Water cooled inverter chillers and
heat pump
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, fans 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
Compressor and fan electrical motors 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. High Temperature Alarm is recorded in the Unit Controller only in case of compressors. Alarm
must be reset from the controller.
Do not operate on a faulty fan before the main switch has been shut off. Overtemperature protection is auto-
reset, therefore a fan may restart automatically if temperature conditions allow it.
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 on the unit will be required in order to solve the problem. In case
of a phase reversal alarm two phases requires to be inverted.
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