130 - 23/May/97
6.6 SAFETY ASPECTS
Noise suppression of Motor and Drive systems involves consideration of the earthing
system, and its effectiveness at high frequencies. It should not be forgotten that is the safety
system too and that the safety must take priority over EMC.
To reduce the radiated emissions, the use of capacitance to earth is very effective. In fact all
Vickers drives have Y-type capacitors near the input power supply connector and Schaffner
filters also include them. These capacitors conduct current from phase to earth; this can be
in the order of hundreds of milliamperes. Appropriate safety measures should be taken to
ensure that this potentially dangerous current flows to earth.
CAUTION: the input Y-type capacitors from line to earth of all Vickers drives are
rated 2700 Vdc for Voltage Test between terminals. To carry out the
"AC Voltage Test" of the EN 60204-1 (par.20.4), according to
Machinery Directive (89/392/EEC) and to Low Voltage Directive
(73/23/EEC), it is recommended to disconnect these capacitors.
Please ask the Service Centers for the correct procedure.
Schaffner filters are rated 2800 Vdc for Voltage Test between line
and earth. It is recommended to disconnect the filter in order to carry
out the "AC Voltage Test" of the EN 60204-1 (par.20.4).
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