Siemens 6RA7086-6KS22 Operating Instructions Manual page 718

Maintenance
13.2.3 Replacement of diodes and thyristor modules for devices up to 1200A
The diodes and thyristor modules are mounted by means of self-tapping screws. When a module is
replaced, the support surfaces on the heatsink must be cleaned and a new layer of thermo-
lubricant applied to the thyristor module. To fix the modules always used screws with a metric
thread of the same length as the original screws and fixing elements (washer and spring lock
washer). When screwing the modules to the busbars and boards, also use screws with a metric
thread and the same length as the original screws and fixing elements (washer and spring lock
washer).
The layer of thermo-lubricant (silicone-free, type H-T-C made by Electrolube) applied to the modules must
be so thin and even that the baseplate is still clearly visible underneath!
No auxiliary cathodes must be contacted on the standby modules!
Tightening torque on module: 3,5 Nm
Tightening torque of current terminals: 3 Nm
Tightening torque on module: 6 Nm
Tightening torque of current terminals: 12 Nm
13-8
NOTICE
Module design
Tightening torque on module: 3,5 Nm
Tightening torque of current terminals: 5 Nm
Tightening torque on module: 6 Nm
Tightening torque of current terminals: 15 Nm
SIEMENS AG
SIMOREG DC Master Operating Instructions
05.05
6RX1700-0AD76