ADVANCED OPERATION - Section 5
MTS-3000 SERIES OPERATION AND REFERENCE MANUAL 5-11
CU M004 01A
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5.2.12.2 SLOPE.
The slope display option is used when testing the slope characteristic of a transformer differential relay.
Slope is defined as:
Slope = Ioperate / Irestraint,
Where Ioperate is the difference current: Iop = |I1 – I2|,
The formula for restraint current is dependent on the relay type.
Three Winding Relays
(3 wdg BDD style).
Three coil T-connection electromechanical relays (see Figure 3.16) calculate the restraint current as the
average of the two restraint currents:
Irestraint = (I1+I2) / 2
for
3 wdg BDD style relays
Two Independent Coil Relays ( 2 wdg style).
Modern two independent coil type differential relays (see Figure 3.17) typically use the greater of the two
restraint currents.
Irestraint = Max ( I1, I2) for 2 wdg 87T style relays
5.2.12.3 IMPEDANCE.
The Impedance option is used when testing distance or impedance relays. The formula used will change
automatically depending on the fault mode the MTS-3000 is in.
Phase to neutral faults (
φφφφ
-N)
Z
1
= V / (I + KI)
This display mode displays the positive sequence impedance (Z
1
) for phase to ground faults. Ground fault
impedance relays are required to respond to the positive sequence impedance of a line to ground fault.
However, they’re supplied with
φ
-N voltage and phase current, plus a determined proportion of the
residual current. This proportion of the residual current is the zero sequence compensation factor, K.
7 L P H
= # # # 3 1 3 3 3 #
V H F
7 L P H
= # # # 3 1 3 3 3 #
V H F
7 L P H
= # # # 3 1 3 3 3 #
V H F
7 L P H
= # # # 3 1 3 3 3 #
V H F
6 O R S H
= # # 5 4 1 3 : #
6 O R S H
= # # 5 4 1 3 : #
6 O R S H
= # # 5 4 1 3 : #
6 O R S H
= # # 5 4 1 3 : # (
φφφφ
9
0
,
= # # # # 3 1 3
9
0
,
= # # # # 3 1 3
9
0
,
= # # # # 3 1 3
9
0
,
= # # # # 3 1 3
°°°°
9 H F W R U
#
5 R W D W H
#
$
9 H F W R U
#
5 R W D W H
#
$
9 H F W R U
#
5 R W D W H
#
$
9 H F W R U
#
5 R W D W H
#
$
7 L P H
= # # # 3 1 3 3 3 #
V H F
7 L P H
= # # # 3 1 3 3 3 #
V H F
7 L P H
= # # # 3 1 3 3 3 #
V H F
7 L P H
= # # # 3 1 3 3 3 #
V H F
, P S H G
=
, P S H G
=
, P S H G
=
, P S H G
=
####
7 1 : 8 6
7 1 : 8 6
7 1 : 8 6
7 1 : 8 6
Ω
Ω
Ω
Ω
φφφφ
9
0
,
= #
9
0
,
= #
9
0
,
= #
9
0
,
= #
####
# : 8 1 ; 5
# : 8 1 ; 5
# : 8 1 ; 5
# : 8 1 ; 5
°°°°
φφφφ
0000
1
= #
1
= #
1
= #
1
= #
) O W
#
3 K D V H
#
$
) O W
#
3 K D V H
#
$
) O W
#
3 K D V H
#
$
) O W
#
3 K D V H
#
$