Technical Guide
Testing self-powered relays with SVERKER 900
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SVERKER 900 with indication “Current generator MkII” is designed to test self-powered relays.
It is important to be aware that the technology behind self-powered relays is in continuous and fast development
(see par. 2), so it cannot be promised that all self-powered relays are managed. Please contact Megger if you
need support.
4. General information about overcurrent relays.
4.1. IEC standard for overcurrent protection: IEC 60255-151:2009
The IEC standard for overcurrent protection function is IEC 60255-151:2009: Measuring relays and protection
equipment - Part 151: Functional requirements for over/under current protection [8].
The information, definitions and testing methodologies described in the IEC relay protection functional
standards, IEC 60255-1xx are of interest for [9]:
-
protection relay manufacturer, where the standards describe the minimum requirements for type-testing,
-
test equipment manufacturer
–to apply the standardized test methodologies
-
end-users, for procurement specification, acceptance tests
-
the entire relay protection community in general (as well as for commissioning / testing engineers), for using
the same terminology and definitions
If all the parties have a competence of IEC 60255-1xx standards, there will be less misunderstandings during
the purchase but also at commissioning/maintenance of the protection relays, with less discussions, shorter
testing times and a more reliable protection system [10],[7].
The following paragraphs summarize the most important details available in the standard that are useful for the
work of a relay testing engineers.
4.1.1. Standardized IEC inverse time curves
One of the most important successes of IEC 60255-151:2009 was to reach an international consensus on the
harmonisation of the so-called
“IEC and IEEE time curves”. The recent IEEE standard C37.112: 2018 [11] has
in principle adopted the same IEC curves.
The standardized IEC curves are A, B, C, D, E and F. The common names used for the curves are associated
to the letters (Figure 4). SVERKER 900 has implemented the standardized curves, as the next paragraphs will
show.
