ABB Switchsync F236 User Manual

Controlled Switching — Buyer´s Guide
G-3
Edition 2, 2006-09
Transmission Lines Application
Switching of Transmission Lines
Control of Closing and Reclosing
Operations, Shunt Compensated
Lines
For shunt compensated lines, the interaction
between line capacitance and reactor induc-
tance will lead to voltage oscillations of the
healthy phases after interruption. In this case,
due to the oscillating voltage shape on the
line, the voltage transformers connected to
the line will provide correct voltage signals.
Controlled switching requires use of single-
pole operated line circuit breakers. Reclosing
may be set to occur slightly after (time de-
pending on RDDS) phase-to-ground supply
side voltage zero. A suitable controller is the
Switchsync™ F236, connected in the same
manner as for uncompensated line.
Control of Closing and Reclosing
Operations, Series Compensated
Lines
For the time being, no suitable method is
available for limitation of switching overvol-
tages on series compensated lines by use of
controlled switching.
Reduction of Overvoltages when
Using Controlled Line Switching
The actual limitation of switching overvoltag-
es that will be achieved by use of controlled
line switching depends on several factors,
such as:
- line length and configuration
- degree of compensation
- single- or three-pole reclosing
- type of Switchsync™ controller utilized
- position and type of surge arresters
The acceptable switching overvoltage level
depends on the insulation level of the sys-
tem.
Due to the variation of parameters, the
choice of Switchsync™ controller must be
made on a case-by-case basis, and often
requires a study of the switching overvoltag-
es that may occur. ABB is prepared to par-
ticipate in such studies. The best solution is
often a combination of Switchsync™ control-
ler and surge arresters. Such surge arresters
may be placed at line ends, as a normal part
of the protection system for the substations,
but may also be placed along the line. See
Figure 4.
Figure 4.
Transmission Line arresters (PEXLINK) in an 800 kV
system, USA. Utilized for limitation of switching
overvoltages.
An example of the variation of switching
overvoltage limitation achieved with different
combinations of Switchsync™ controllers
and surge arresters is shown in Figure 5.
Use of Switchsync™ control gives adequate
overvoltage reduction, without need for pre-
insertion resistors and the related complexity
of the circuit breakers.
Solutions with Switchsync™ control are
particularly beneficial in breaker-and-a-half
configurations, where a circuit breaker may
switch different objects, e.g. sometimes a
transformer and sometimes a line. In such
cases, it may be difficult to choose pre-inser-
tion resistors that are suitable for both ap-
plications.

ABB Switchsync F236 Specifications

General

Brand	ABB
Model	Switchsync F236
Category	Controller
Language	English