Multifunction Protection and Switchgear Control unit REF542plus
Manual: Motor Protection with ATEX-Certification
4.5.3 Functional check
For a functional check of the unbalanced load protection, we recommend to use
three-phase testing equipment. By switching the phase sequence (e.g. L1, L3, L2) at
the connections, a unbalanced load current can be simulated. The amplitude of the
symmetrical conventional tripping current, related to the rated current, is identical to
the size of the unbalanced load current to be checked.
If only single-phase testing equipment is available, the conventional tripping current
can be connected either via two conductors, e.g. L2 and L3, or only to one conductor,
e.g. L1. If the tripping current is connected to two conductors, the conventional trip-
ping current has to be increased in accordance with the following equation
)(3pol3L3)-(L22 II = (24.)
so that the behavior can be checked properly. In the case of a conventional tripping
current injection in one of the conductors, the conventional tripping current has to be
increased by factor 3 in accordance with the equation below
)(3pol3(L1)2 II =
(25.)
1VTA100114-Rev. 04 en PTMV, 19.01.05 Motorprotection 31 / 66
Valid from Version V4D02
To Next Page
Loading...
