Page 1013 - Industrial Power Engineering and Applications Handbook

32/958 Industrial Power Engineering and Applications Handbook
where ZR, Zy, IB are the phase currents in the three phases The procedure for tests and the requirements of the test
results will remain the same as for the type tests,
"'
per
:. Impedance, Z = - phase/rn
i2
Iph '
32.5 Field tests
and R=- Q per phaselm
3Zih . L
These are generally the same as the routine tests. No
and X = 4- R per phase/m field test as regards the power frequency voltage withstand
or HV test is normally prescribed on a bus system, which
where has already been tested at the manufacturer's works.
P = total power input in watts Repeated application of high voltage may deteriorate the
L = length of the bus section on which the voltage drop insulating properties of the insulation system and its life
has been measured in metres unless modification has been carried out at site or where
the insulation of joints between the busbars can be
32.3.11 Endurance of trunking system with completed only after erection at site. In such cases, if
trolley-type tap-off facilities this test becomes essential it can be conducted,

This test is generally applicable to an LT overhead busbar At 85% of the test values in Table 32.1(A) for LT
system or rising mains which have sliding-type plug-in systems, applied for 1 minute.
boxes for outgoing terminations (Figures 28.3 and 28.4(a)). Or at 80% of the test values for HT systems for
The sliding contacts carrying their rated current at rated 1 minute.
voltage must be able to operate at least 10 000 times to Or a d.c. voltage as in Table 32.1(B) applied for
and fro with the trunking conductors. A successful test 15 minutes as in IS 8084.
should reveal no mechanical or electrical defect such as Or at 75% of the test values in Table 32.2, for series I1
pitting, burning or welding of contacts. voltage systems according to ANSI C-37/20C.

Note
32.4 Routine tests If it is not possible to carry out the test at 75%, 80% or 85% of the
test values, as prescribed above or for some reasons the test duration
may have to be increased by more than one minute, then it is
The tests against step numbers 1,2 and 3 are of a general permissible for the Lest voltage to be further reduced to suit the site
nature and no test procedure is prescribed for these. The and instead, the test duration increased The reduced test voltages
remainder have already been covered under type tests. for longer test durations are provided in Table 14.8.

Relevant Standards
IEC

602981 1990 A.C. metal enclosed switchgear and controlgear for rated voltages 3427/1991 BS EN
above kV and up to and including 52 kV 60298/ 1996
60439-211987 Specification for low voltage switchgear and controlgear assemblies 8623-2/1993 BS EN 60439-
Particular requirements for busbars trunking systems (busways) 2/1993
6069411996 Common specifications for high voltage switchgear and 3427/ 199 1 BS EN
controlgear Standards 60694/1997
Specification for high voltage busbars and busbar connections 8084- 1992 BS 159/1992

Relevant US Standards ANSVNEMA and IEEE
~ ~~~
NEMA 107/1993 Method of measurement of Radio Influence Voltage (RIV) of HV apparatus
ANSMEEE-C-37- Metal enclosed bus and Guide for calculating losses in isolated phase bus.
23/1992
ANSI/IEEE-C37.24/ Guide for evaluating the effect of solar radiation on outdoor metal enclosed switchgear
1986
Notes
1 In the tables of Relevant Standards in this book while the latest editions of the Standards are provided, it is possible that revised editions
have become available. With the advances of technology and/or its application, the updating of Standards is a continuous process by
different Standards organizations. It is therefore advisable that for more authentic references, readers should consult the relevant
organizations for the latest version of a Standard.
2 Some of the BS or IS Standards mentioned against IEC may not be identical
3 The year noted against each Standard may also refer to the year of its last amendment and not necessarily the year of publication.