IG-287-EN version 03; 24/07/2020
27
General Instructions
transforma
.plur: Transformers with corrugated tank
and submerged in dielectric liquid from 3150 kVA
Final annex
9. Final annex
9.1. Tightening torques
The torques recommended for the connections are as
follows:
Recommended tightening torques [Nm]
Metric size
M10
M12
M16
M20
M30
Wrench size
17
19
24
30
46
Low voltage
(LV)
• Connection between nuts.
15-20
70-100
250-350
• Fastening the palms to the pin (stainless steel bolts).
25-35
40-60
• Bolts to the surface of the palms.
25-35
40-70
100-150
• Connections at low voltage busbars (steel bolt and nut).
45-60
65-85
95-130
Medium or
high voltage
(MV or HV)
Fastening the bushings to the medium voltage (MV) bolt
10-15
(Brass bolt and nuts)*
Bolts to the surface of the palms or rods
25-35
40-70
100-150
* The medium voltage terminals include three nuts, but only the top two can be handled. The purpose of the lower nut is to tighten the insulator gasket; if
it is loosened, it could cause leakage of the dielectric liquid.
Table 9.1.
Tightening torques
