Element
BI Inhibits
37-1
37-2
Element Blocking from Current Guard
The elements can be blocked by the undercurrent guard function. This functionality should be checked.
Element
Guard Setting
Blocked
37-1
37-2
Check correct phase indication, trip output, alarm contacts, waveform record.
37G Undercurrent Earth Fault – Measured
If 2 undercurrent 37G elements are used with different settings, it is convenient to test the element with the
lowest setting first. The higher setting element can then be tested without interference from the other
element.
Apply current to the single phase input at a level above the undercurrent 37G-n setting until the element
resets.
If DTL setting is small, gradually reduce current until element operates.
If DTL is large apply 1.1 times setting, check for no operation, apply 0.9 times setting, check operation.
Apply 0.5 times setting current and record operating time.
Phase
I
set
(Amps)
DTL (sec)
P.U. Current
Amps
Tolerence
Op. Time 0.5 ⋅
I
set
Tolerance
CT4(I
G
)
Element Blocking
The undercurrent elements can be blocked by
Binary Input Inhibit
. This functionality should be
checked.
Element
BI Inhibits
37G-1
37G-2
Element Blocking from Current Guard
The elements can be blocked by the undercurrent guard function. This functionality should be checked.
Element
Guard Setting
Blocked
37G-1
37G-2
Check correct phase indication, trip output, alarm contacts, waveform record.
46 Negative Sequence Overcurrent Protection
Where 2 NPS elements are being used with different settings, it is convenient to test the elements with the
highest settings first. The elements with lower settings can then be tested without disabling the lower
settings. The thermal withstand limitations of the current inputs, stated in the
Technical Data
should
always be observed during testing.
NPS overcurrent can be tested using a normal 3P balanced source. 2 phase current connections should be
reversed so that the applied balanced 3P current is negative phase sequence.
9.10.6
9.10.7
Functional Tests
9.10 Protection Functional Tests
426
Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019