Total Versus Individual Readings; Measurement Strategy - ABB Excount II User Manual

4. Using the transceiver

4.10 Total versus Individual readings

Attempts to make a total reading (available in extended version only)
– i.e. consecutively leakage current, surge count, resistive current – may
be inappropriate with certain configurations and generate errors, since
the information is "in the air" too long. Should this occur, individual
readings of the separate measurements need to be made instead. See
section 5.3. Note that different contact zones may apply for each indivi-
dual reading.

4.11 Measurement strategy

To avoid unnecessary outages plus the high cost of unwarranted testing
of arresters, a decision should be made on a suitable time interval for
regular reading of the EXCOUNT-II data. This interval depends on a
number of factors including network arrangement, lightning flash density,
system redundancy, resources, desired accuracy in time-stamp, etc.
As a guide, the following strategy for a schedule of taking measurements
is proposed to begin with:
• Always a short time directly after energization to obtain a reference
value.
• At regular time intervals, determined by site availability and importance.
Two readings per year is a reasonable starting point but more may be
warranted, especially in locations where the arresters are exposed to
high lightning activity and/or heavy atmospheric pollution.
• Specifically in advance of the designated lighting season and thereafter
following periods with bad weather conditions.
• After special fault conditions causing flashover in the network or TOV's
of high amplitude and/or long duration.
Readings must be made more often and with short regular time intervals
if the intention is to correlate the EXCOUNT-II data with other external
measurements and recordings - lightning activity meters, SCADA, etc.
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1HSA 801 080-15en EXCOUNT-II Users Manual