Table 9-5 P.U. D.O. & Timing Tests
Ph. Dir Char.
(NI EI VI
LTI,
DTL)
I
set
(A) Tm Operate Current Operate Time
P.U.
(Amps)
D.O.
(Amps)
Tol 2 ⋅ I
set
(sec)
5 ⋅ I
set
(sec)
Tol
CT4
Calculated timing values in seconds for Tm = 1.0
Curve 2 ⋅ I
set
5 ⋅ I
set
IEC-NI 10.03 4.28
IEC-VI 13.5 3.38
IEC-EI 26.67 3.33
IEC-LTI 120 30
ANSI-MI 3.8 1.69
ANSI-VI 7.03 1.31
ANSI-EI 9.52 1.3
Note that the operate time may be subject to the Minimum Op Time setting for the element and/or may
have a follower DTL applied.
If VTS action is set to Block, this option should be tested. Apply balanced voltage and current. Reduce a-
phase voltage to cause a VTS condition. Increase a-phase current and check that the element does not
operate.
If VTS action is set to Non-Directional, this option should be tested. Apply balanced voltage and current.
Reduce a-phase voltage to cause a VTS condition. Increase a-phase current and check that the element oper-
ates at its normal setting. Reverse the voltage phase direction whilst checking that the element does not reset.
Element Blocking
The Measured Earth Fault elements can be blocked by Binary Input Inhibit, VT Supervision
and Inrush Detector operation. The characteristic can be made non-directional by VT Supervision.
This functionality should be checked.
Element
BI Inhibits VTS Action 81HBL2 Inhibit
51G-1
51G-2
51G-3
51G-4
50G-1
50G-2
50G-3
50G-4
ANSI Reset
If the element is configured as an ANSI characteristic, it may have an ANSI decaying reset delay applied.
ANSI reset times from operated condition to fully reset are as follows for zero applied current and Tm = 1.0.
The reset curve characteristic type and Tm is defined by the operating characteristic.
Curve
Fully Operated to Reset with Zero Current Applied
& Tm = 1 (s)
ANSI-MI 4.85
ANSI-VI 21.6
ANSI-EI 29.1
Functional Tests
9.10 Protection Functional Tests
434 Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019
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