Siemens 7SR51 - Undercurrent Earth Fault - Measured

Phase I
set
(Amps) DTL (sec) P.U. Current
Amps
Tolerence Op. Time 0.5 ⋅
I
set
Tolerance
CT1(I
A
)
CT2(I
B
)
CT3(I
C
)
Element Blocking
The undercurrent elements can be blocked by Binary Input Inhibit. This functionality should be
checked.
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
9.9.6
Functional Tests
9.9 Protection Functional Tests
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual 469
C53000-G7040-C014-1, Edition 11.2019