Eurotherm 590L Series, Product Manual, Page: 40 / 170

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We do not recommend the use of circuit breakers (e.g. RCD, ELCB, GFCI), but where their use
is mandatory, they should:
•
Operate correctly with dc and ac protective earth currents (i.e. type B RCDs as in
Amendment 2 of IEC755).
•
Have adjustable trip amplitude and time characteristics to prevent nuisance tripping on
switch-on.
When the ac supply is switched on, a pulse of current flows to earth to charge the EMC filter
internal capacitors which are connected between phase and earth. This has been minimised in
Eurotherm Drives filters, but may still trip out any circuit breaker in the earth system. In
addition, high frequency and dc components of earth leakage currents will flow under normal
operating conditions. Under certain fault conditions larger dc protective earth currents may flow.
The protective function of some circuit breakers cannot be guaranteed under such operating
conditions.