TAVRIDA ELECTRIC VCB Series, User Manual

Page: 102 / 142

102
Operation description Required tool Approximate timing
Primary circuits contact resistance check
1)
ISM shall be closed before the test, there
should not be any external circuits
connected to ISM main terminals that
provide parallel circuit with the ISM main
circuits otherwise tests will be invalid. Visual check, no tool is required 1 minute
Test equipment shall be connected to ISM
main circuits terminals according to Figure
155 in order exclude any additional
contact resistance and to decrease
measurement error. Main contact
resistance shall be measured by
appropriate equipment at test current not
less than 50 A. Resistance measurement test
equipment with test current not less
than 50 A
10 minutes
Measured values for VCB15_LD,
VCB25_LD and VCB15_MD must not
exceed limits specified in Table 1
1)
Measured values for VCB15_Shell and
VCB15_HD must not exceed limits
specified in Table 1 increased on 2
μOhm.
These 2
μOhm are added by contact
resistance between ISM terminals and
additional burs attached to them (see in
the Figure 155)
Visual check, no tool is required -
1) If the Module has contact resistance which exceeds the specified limit but is less than twice this limit, continuation of use is possible, if actual
continuous current does not exceed the following value:
where:
Ia, Ra
— actual current and corresponding contact resistance,
Ir, Rr
— rated values (Table 1).
If the contact resistance is at least twice as high as the specified limit, the ISM must be replaced.
Additionally switchboards can be subjected to extra tests that are specified in corresponding documentation for the switchboards.