Vector Groups Dy5
High Side CT 100 A/1 A (CT
Ι
= 100)
The following fault currents may be detected at the low side:
If 46-1 PICKUP on the high side of the devices is set to = 0.1, then a fault current of Ι = 3 · TR
V
· TR
Ι
· 46-1
PICKUP = 3 · 110/20 · 100 · 0.1 A = 165 A for single-phase faults and √3 · TR
V
· TR
Ι
· 46-1 PICKUP = 95 A can
be detected for two-phase faults at the low side. This corresponds to 36% and 20% of the transformer nominal
current respectively. It is important to note that load current is not taken into account in this simplified
example.
As it cannot be recognized reliably on which side the thus detected fault is located, the delay time 46-1
DELAY must be coordinated with other downstream relays in the system.
Pickup Stabilization (definite-time overcurrent protection)
Pickup of the definite time elements can be stabilized by means of a configurable dropout time. This dropout
time is set in 4012 46 T DROP-OUT.
Inverse Time Tripping Curve
Several IEC and ANSI curves are available if your operational equipment requires the use of a curve-dependent
tripping characteristic. They are selected at address 4006 46 IEC CURVE or at address 4007 46 ANSI
CURVE
It must be noted that a safety factor of about 1.1 has already been included between the pickup value and the
setting value when an inverse time characteristic is selected. This means that a pickup will only occur if an
unbalanced load of about 1.1 times the setting value 46-TOC PICKUP is present (address 4008). Dropout
occurs as soon as the value falls below 95 % of the pickup value. When selecting the ANSI curve in address
401146-TOC RESET the Disk Emulation, dropout will be performed according to the dropout curve as
explained in the function description.
The associated time multiplier is specified at address 4010, 46-TOC TIMEDIAL or address 400946-TOC
TIMEDIAL.
The time multiplier can also be set to ∞. After pickup the element will then not trip. Pickup, however, will be
signaled. If the inverse time element is not required at all, address 140 46 should be set to Definite Time
during the configuration of protection functions (Section 2.1.1.2 Setting Notes).
Settings
Addresses which have an appended “A” can only be changed with DIGSI, under “Additional Settings”.
The table indicates region-specific default settings. Column C (configuration) indicates the corresponding
secondary nominal current of the current transformer.
Addr.
Parameter C Setting Options Default Setting Comments
4001 FCT 46 OFF
ON
OFF 46 Negative Sequence
Protection
4002 46-1 PICKUP 1A 0.05 .. 3.00 A 0.10 A 46-1 Pickup
5A 0.25 .. 15.00 A 0.50 A
4003 46-1 DELAY 0.00 .. 60.00 sec; ∞ 1.50 sec 46-1 Time Delay
4004 46-2 PICKUP 1A 0.05 .. 3.00 A 0.50 A 46-2 Pickup
5A 0.25 .. 15.00 A 2.50 A
4005 46-2 DELAY 0.00 .. 60.00 sec; ∞ 1.50 sec 46-2 Time Delay
4006 46 IEC CURVE Normal Inverse
Very Inverse
Extremely Inv.
Extremely Inv. IEC Curve
2.7.4
Functions
2.7 Negative Sequence Protection 46
136 SIPROTEC 4, 7SJ80, Manual
E50417-G1140-C343-A8, Edition 12.2017
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