|
Why
Many powergrids today are characterised by the long distances
between generation and the consumers. Therefore long wires with variable loads
are common. That brings the use of capacitor banks to compensate the loss of
effect. Switching theese banks causes transients. The transients causes problems
on the power grid.
Therefore some breakers are connected with switch sync
mechanisms which allow for the breaker to operate at voltage
zero crossing. By point-on-wave switching at the most
appropriate moment, inrush currents or repercussions can be
reduced to non-critical values.
Shunt capacitor
banks
Basic aim is to control closing to minimize the energizing
transients (voltage transients as well as inrush currents). To
improve interrupting performance, controlled opening can also be
utilized.
Shunt reactors
Basic aim is to control de-energizing to ensure reignition-free
behavior. In addition, controlled closing also serves as a
useful method for minimizing inrush currents.
No-load transformers
The purpose of controlled no-load transformer switching is to
minimize the inrush currents (and voltage distortion) by taking
residual flux into account. Depending on the type of application
and type of controller, controlled opening can serve as support
for controlled closing.
No-load overhead lines
Controlled re-energizing or energizing of overhead lines
ensures minimized switching transients.
The SA10 equipped with an FSU10 offers you the following measurement
possibillities:
When using FSU10 together with the SA10 you can fully test your
controlled switching CB’s. Line currents and voltage are
displayed at the same time as any other inputs connected to the
breaker.
Analysis is made manually by oscilloscope functions or automatic
by the software representing numeric results. Limits and
warnings can be implemented if required.
To verify the switch sync performance, the following should be
recorded:
- Busbar voltages
(or at least the reference voltage)
- Current in each phase
- Output commands from controller
- Functioning times of precision auxiliary
contacts (if adaptation control is used)
- Monitor the signal from the control room that initiates the relay.
- See the signals out from the relay to the breaker trip and close coils.
- The main contact can be connected to verify the switching.
The Equipment
The
FSU10 (ArtNo: S150) is a plug-in box to the SA10 and it comes complete with current clamps
for easy testing. This equipment also allows for first
trip measurement.
|
