Functions
6-917SJ62 Manual
C53000-G1140-C121-1
If the pickup setting (PU) of the device on the high side is set to 0.1 A, then a phase-
to-ground fault current of
I = (1/0.33) * CTR * PU * V
HS
/ V
LS
=
3 * 100 * 0.1 A * 110 kV / 20 kV = 165 A
and a phase-to-phase fault current of
I = (1/0.58) * CTR * PU * V
HS
/ V
LS
=
1.732 * 100 * 0.1 A * 110 kV / 20 kV = 95 A
can be detected at the low side. These faults correspond to 36 % and 20 % of the base
transformer rating respectively. It is important to note that load current is not taken into
account in this simplified example. To prevent false operation for faults in other zones
of protection, the delay time must be coordinated with other relays in the system.
Inverse Time Ele-
ment with IEC
Curves
If the 46-TOC element is employed, a characteristic tripping curve should be selected
to coordinate with the thermal overload curve representing the protected equipment
(e.g. induction motor, etc.). The curve should be selected at address ,(&
&859(. The characteristic tripping curves, and the formulas on which they are based,
are given in the Technical Specifications, Section 10.8.
The 46-TOC element picks up when the negative sequence input current exceeds
110% of the pickup settings and drops out when he negative sequence current de-
creases to 95 % of the pickup setting. The pickup settings is entered at address
72&3,&.83.
The associated time multiplier is entered at address 72&7,0(',$/.
The time multiplier may also be set to ∞ thus allowing the element to pickup and gen-
erate a message, but never to trip. If the inverse time element is not required at all,
address should be set to LQGHSHQGHQW
during configuration of protective func-
tions (Section 5.1).
Inverse Time Ele-
ment with ANSI
Curves
If the 46-TOC element is employed, a characteristic tripping curve should be selected
to coordinate with the thermal overload curve representing the protected equipment
(e.g. induction motor, etc.). The curve should be selected at address $16,
&859(. The characteristic tripping curves, and the formulas on which they are based,
are given in the Technical Specifications, Section 10.8.
The 46-TOC element picks up when the negative sequence input current exceeds
110 % of the pickup settings and drops out when the negative sequence current de-
creases to 95 % of the pickup setting. The pickup settings is entered at address
72&3,&.83. If 'LVN (PXODWLRQ was selected at address 72&5(
6(7, reset will occur in accordance with the reset curve as described in Subsection
6.7.1.3. The associated time dial is entered at address 72&7,0(',$/.
The time may also be set to
∞ thus allowing the element to pickup and generate a
message, but never to trip. If the inverse time element is not required at all, address
should be set to 'HILQLWH7LPHRQO\
during configuration of protective func-
tions (Section 5.1).
6.7.2.1 Settings for Negative Sequence (Phase Balance) Current Protection
In the list below, the setting ranges and default setting values for the pickup currents
are for a device with a nominal current rating I
N
= 5 A. For a nominal current rating I
N
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