Download Insulation Coordination and Transients

Insulation Coordination and Transients
Overvoltage protection for system equipment
At a glance
Insulation coordination ensures that all equipment is properly protected against lightning,
switching and fundamental-frequency overvoltages. Siemens Power Technologies International (Siemens PTI), the provider of network
consulting, software solutions and T&D training
within Siemens Energy:
„ Advises in all matters affecting development,
tendering, bids, project engineering and plant
operation
„ Calculates possible maximum overvoltage
stresses for new installations to be built in the
future or measures them in existing ones with
our specialized measuring equipment
„ Finds the reason of an outage in case of
system device (e.g. transformer) failure
We propose mitigation measures in order to
protect expensive equipment sufficiently, but for
reasonable costs.
The challenge
A large amount of money is invested in MV and
even more in HV equipment, which can be
destroyed in seconds by overvoltages if not
protected properly. Therefore, a thorough consideration of overvoltage issues is a major point
in order to protect the investments made, not to
speak of reliability of supply, economic costs of
outages etc. Typically, a proper insulation coordination and protection against overvoltages
requires only a small fraction of the amount of
money which would have to be spent in case of
equipment failure. That is why already in the
planning process the consideration of a sufficient overvoltage protection is a must.
protection level against lightning overvoltages for the equipment
„ Investigation of HV circuit breaker stresses
under various system and fault conditions
(TRV, transient recovery voltage)
„ Definition of overvoltage protection for MV
switchgear, in particular for special cases
such as arc furnace breakers or compensation reactors
„ Investigation of breaker stresses used for
switching of capacitors
These and other investigations require a profound knowledge of the physical phenomena
themselves as well as the modeling of the network for the high frequencies involved. Our
specialists have many years of experience with
a large variety of special switching and lightning
phenomena. They know how to model the appropriate system scenarios and are able to
decide on the proper countermeasures and
protection devices.
Measurements
For the measurement of MV and LV overvoltages and transient phenomena we have special
measuring equipment. We have long-term experience in measuring voltages and currents up
to the MHz frequency range. Especially for the
clarification and investigation of equipment
failures, measuring the transient phenomena in
a network frequently proves the hypothesis
regarding the cause of the outage or point out
further problems.
Our solution
Insulation coordination includes a variety of
typical tasks requiring special attention in the
planning process. Just to mention a few:
„ Surge arrester placing and rating in HV
switchgear and provision of a sufficiently high
Siemens PTI − Network Consulting
Figure 1: Measurement of switching transients in a 20 kV
industrial installation
Published by and copyright © 2009:
Siemens AG
Energy Sector
E D SE PTI
Freyeslebenstrasse 1
91058 Erlangen, Germany
Siemens Energy, Inc.
Power Distribution, T&D Service Solutions
Siemens Power Technologies International
400 State Street
PO Box 1058
Schenectady, NY 12301-1058
For more information, please contact
our Customer Support Center.
Phone: +49 180 524 70 00
Fax:
+49 180 524 24 71
(Charges depending on provider)
E-mail: [email protected]
www.siemens.com/energy/power-technologies
Siemens Transmission and Distribution Ltd
PTI
Sir William Siemens House, Princess Road
Manchester, M20 2UR
United Kingdom
Power Distribution Division
Printed in Germany
Printed on elementary chlorine-free
bleached paper.
All rights reserved.
Trademarks mentioned in this document
are the property of Siemens AG, its affiliates,
or their respective owners.
Subject to change without prior notice.
The information in this document contains general
descriptions of the technical options available,
which may not apply in all cases.
The required technical options should therefore be
specified in the contract.
NC2510-EN-200905