ABB SDG-1T Instruction Leaflet

Effective: December 1996
Supersedes I.L. 41-496.52C, Dated January 1987
( | ) Denotes Changed Since Previous Issue
!
CAUTION
Before putting relays into service, remove
all blocking which may have been inserted
for the purpose of securing the parts dur-
ing shipment, make sure that all moving
parts operate freely, inspect the contacts
to see that they are clean and close prop-
erly, and operate the relay to check the set-
tings and electrical connections.
1. APPLICATION
Type SDG-1T, 2T and 4T relays are single zone
ground distance relays used to detect faults on sub-
transmission or transmission lines. Table I shows the
particular application intended for each relay and the
components included.
The I fault detector prevents potential circuit trouble
0
from causing immediate trip. The frequency verifier
should be utilized for all high speed trip applications
to avoid tripping on line energization or other condi-
tions that cause high frequency transients.
The phase-to-phase desensitizer is used to eliminate
a possible overreach on two-line-to-ground faults.
This circuit is needed for Zone1 applications. It is not
needed for overreaching applications. The nature of
All possible contingencies which may arise during installation, operation or maintenance, and all details and
variations of this equipment do not purport to be covered by these instructions. If further information is
desired by purchaser regarding this particular installation, operation or maintenance of this equipment, the
local ABB Power T&D Company Inc. representative should be contacted.
Printed in U.S.A.
ABB Power T&D Company Inc.
Power Automation & Protection Division
Coral Springs, FL 33065
Relay
SDG-1T
SDG-2T
SDG-4T
Note 1:
the design is that the phase-to-phase desensitizer is
removed from service on settings S = 2 or S = 3.
The potential supply must be 4 wire Wye-grounded.
The broken delta voltage connection is provided inside
the relay.
Mutual compensation is not required with these relays.
With an 85% Zone1 setting and an extreme zero-
sequence mutual impedance, the relay will reliably
reach ground faults on at least 70% of the protected
line.
All three relays are equipped with normally open out-
put contacts and ICS's for indicating trip coil current
flow. In addition the SDG-4T has a normally-closed
contact for "contact-opening-carrier start".
Type SDG-1T, -2T, -4T
Static Ground Distance
Table 1
Phase-to-
I 0
Fault Freq. Desensitizer
Det Verifier (Note 1)
X X
– X
– –
For time delayed trip disconnect 2Ø-G circuit. A switch
is provided for this function in the SDG-1T.
Instruction Leaflet
41-496.52D
Phase
Application
X Zone-1 or Zone-2
X Zone-1 or Zone-2
– Blocking
Carrier Start