Experimental verification of a new method of loop resistance testing in low voltage systems with residual current devices

摘要

A periodical verification of the effectiveness of protection against electric shock shall be performed in low voltage systems. The scope of this verification includes loop impedance/resistance testing. If a residual current device is installed in a tested circuit, this testing is problematic. A residual current device trips out during the test, because of the high value of measurement current. This precludes the execution of the test. In the paper a new method of loop resistance testing in low voltage systems is presented. Experimental verification of this method has proved that it enables performing the verification of the effectiveness of protection against electric shock without nuisance tripping of residual current devices. The advantage of this method is the high value of the measurement current - many times higher than the rated residual operating current of commonly used residual current devices. It is very important in terms of measurement accuracy.