Generator circuit experience conditions that are much
more severe and demanding than normal distribution or transmission circuits.
The requirements of generator circuit breaker – installed between generator and
step-up transformer differs from that of distribution or transmission circuit breakers.
The need for first industry standard for generator circuit breakers (GCB) was recognized
by electric utility to protect generating stations. In 1993, Switchgear
Committee of the Institute of Electrical and Electronics Engineers (IEEE)
developed and issued a special industry standard (IEEE C37.013) to address
these special requirements of generator circuit breaker. After de-regulation of
the utility industry and emergence of small packaged power plants, the demand
for small generator circuit breaker is also increasing day by day.
For generator application circuits, special consideration
is given generally to following parameters:
recovery voltage requirement
Above mentioned demanding requirements and required
capabilities of generator circuit breaker are discussed in following paragraphs
in this paper.
II. International standards (IEEE C37.013 &
The IEEE Std. C37.013 was
introduced in 1993 and is the first only applicable standard for generator
circuit breakers in installations with a rated power over 100 MVA and up to
more than 1000 MVA. This standard applies to all ac high-voltage generator
circuit breakers rated on a symmetrical current basis that are installed
between the generator and the transformer terminals. In this standard the
mandatory type testing as well as constructional and operational requirements
are defined. In 2007,a supplement(IEEE C37.013a) was published focusing the
needs of smaller generator circuits ranging from 10 MVA to 100 MVA. A new
working group WG52 was established in 2009, after a decision from IEC and IEEE
boards, in order to create a joint standard under IEC 62271-37-013. In 2015
International Standard IEC/IEEE 62271-37-013 has been released which is
prepared by a joint working group comprised of members both from IEC and IEEE technical
committee. Dual Logo is assigned to this standard. The major benefit of this
standard is that the manufacturer can built one product to cover both IEC and
III. configuration of generator circuits
The simple single line
diagram of a generator circuit breaker connected between a generator and step-up
transformer along with auxiliary transformer & auxiliary motor is shown in
figure 1.Generator circuit breaker is located close to generator and
transformer to minimize the power loss of system and connected with large
cross-section Conductor to reduce the impedance.