MR VACUTAP VV, Инструкции по установке и вводу в эксплуатацию

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5 Mounting
Maschinenfabrik Reinhausen GmbH 2020 62 4349322/01 EN VACUTAP
®
VV
®
5.3.4 Performing DC resistance measurement on transformer
The measured DC current is normally restricted to 10% of the rated current
of the measured transformer winding in order to prevent the winding from
overheating.
Perform the DC resistance measurement in various on-load tap-changer op-
erating positions. You need to distinguish here whether the measured cur-
rent is interrupted when changing operating position or not.
Status of oil compart-
ment Without interruption in
measured current With interruption (mea-
sured current = 0 A be-
fore change of operating
position)
Oil compartment empty Maximum 10 A DC Maximum 50 A DC
Oil compartment filled with
insulating fluid Maximum 50 A DC Maximum 50 A DC
Table 6: Maximum permitted measured currents when performing DC resistance measurement
on transformer
5.3.5 Drying on-load tap-changer in autoclave
NOTICE Damage to the on-load tap-changer!
Moisture in the oil compartment reduces the dielectric strength of the insu-
lating fluid and thus leads to damage to the on-load tap-changer.
► Within 10 hours of drying, seal off oil compartment with on-load tap-
changer head cover.
Dry on-load tap-changer in accordance with the following instructions to en-
sure the dielectric values assured by MR for the on-load tap-changer.
If drying in an autoclave, the following methods are possible:
▪ Vacuum drying
▪ Vapor-phase drying
As an alternative to drying the on-load tap-changer in an autoclave, it can
also be dried in the transformer tank.
5.3.5.1 Vacuum-drying in the autoclave
If you wish to perform another transformer ratio test after drying, proceed as
described in the section "Performing transformer ratio test following dry-
ing" [
► Section 5.3.10, Page 82].