ABB Excount II User Manual page 53

transformer for registration of discharge currents from 10 A and
above, see figure 6.2.1.
The measured current peak values are sorted into five impulse current
ranges and stored in the EXCOUNT-II memory along with the date and
time of each impulse. The impulse current ranges are: 10 - 99 A, 100
- 999A, 1000 - 4999 A, 5000 - 9999 A and >10000 A. The preci-
sion of the impulse current measurements is optimized with regard
to lightning current impulses. The EXCOUNT-II memory keeps the
information on the 1000 most recent impulses, with a maximum rate
of 2 impulses per second. For technical data on surge counting, see
technical data in section 8 on page 52.
Impulse current
transformer
Internal parts of the EXCOUNT-II sensor
The memory content is transmitted to the EXCOUNT-II transceiver, at
the time of the leakage current measurements described below. The
surge counter data is later transmitted to a personal computer and
analyzed by means of the EXCOUNT-II software.
The use of the detailed surge counting information provided by the
EXCOUNT-II is not limited to the estimation of arrester stresses. The
information can also be used to analyse the occurrence of the last
1000 lightning overvoltages with regard to date, time and amplitude
of the arrester impulse current. When this information is combined
with data from event recorders etc., investigations of lightning faults or
other system events may be greatly facilitated.
1HSA 801 080-15en EXCOUNT-II Users Manual
Figure 6.2.1
6. Surge arrester monitoring theory
53