Testing and commissioning
Checking the earth network and locks
General visual inspection
the galvanised steel casing sides are earthed (note: this depends on the earthing
there are no loose metal parts (washers, screws) in the tap-off units.
Note: the results of these checks must have already been noted on the results
sheet by the installation contractor.
Checking insulation between live conductors and earth
Following this check, each link must be reconnected to the upstream transformer
(use the 2
available 6 daN.m torque bolt heads).
Test means: 500V DC megger (DC to avoid capacitive currents)
Measurements: between each phase or neutral
and earth (the casing if it is
connected to earth).
LV circuit insulation value (U < 500 V): 1000 of nominal voltage (IEC 60 439-1)
In all cases, the insulation resistance must not be less than 0.5 M for each link
Note: KT busbar trunking is given for U = 1000 V and Ri = 1 M (value to be taken
into account for all elements: transport and accessories, distribution).
(1) No neutral insulation if the earthing system is such that the neutral is connected to or used
as the earth.
Caution: In this case, once the transformer has been reconnected (star secondary), the phase-
earth measurement is the winding resistance.
PE protective circuit equipotential
Reference: IEC 60 439-1:
Check PE protective circuit continuity by visual inspection and random continuity
The previously performed "phases-PE" insulation test must have been compliant.
Test means: ohmmeter.
To protect personnel by not allowing access to live parts through the use of locks.
Only concerns key operated safety locks.
Checking connections and auxiliary
Check not relevant to busbar trunking.