Chapter 4 - Further Notes; Influence Of Ground Fault Monitoring Devices; Components Susceptible To Interference - Hitachi WJ200 Installation Manual

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Chapter 4 – Further Notes

Influence of ground fault monitoring devices

In the line filter, capacitors are placed between the phases and ground, which can cause larger
charge currents to flow to ground when the filter is first switched on. The amount of this flow has
already been minimized by constructional circuit details. Nevertheless, ground fault monitoring
devices possibly present may be triggered. Ground currents with high-frequency components and
DC components may also flow under normal operating conditions. If faults occur, large DC-
carrying ground currents may flow, possibly preventing the ground fault monitoring device from
responding. For this reason, the use of ground fault monitoring devices is not recommended.
But should they be prescribed in certain applications for safety reasons, you should choose
monitoring devices which are suited for DC, AC and HF ground currents. In addition, you should
ensure that their responsiveness and time characteristics are adjustable, so that a disturbance is not
immediately caused the first time the frequency inverter is switched on.

Components susceptible to interference

The following components must be classified as particularly susceptible to interference from
electromagnetic fields. Special attention should therefore be paid to them during installation:
 Sensors with analog output voltages (< 1 volt)
 Load cells
 Tractive force meters
 Torque measuring hubs
 Resistance thermometer PT100
 Thermoelements
 Anemometers
 Piezoelectric sensors
 AM radios (only long and medium wave)
 Video cameras and TV sets
 Office PCs
 Capacitive proximity switches and filling level sensors
 Inductive proximity switches and metal detectors
 Ripple control transmitters, baby talkers, etc., i.e. all communication devices which use low-
voltage systems as transmission medium
 Devices which do not comply with the pertinent EMC requirements
Chapter 4 – Further Notes


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