3.1Protective surge arresters
WARNING
We recommend the provision of protective surge arresters (supplied by DEHN, type VAV 1000) on the system side. One surge arrester per phase is connected to ground at the input of the common rectifier or rectifier/regenerating unit (use short-circuit-proof lead, fuse protection < 100 A – read data sheet supplied by surge arrester manufacturer!). These are particularly effective in isolated-neutral systems in preventing sparkovers and damage caused by voltage surges in the system. Experience shows that these surge voltages can be several kilovolts in magnitude. They can generate high-intensity secondary arcs when sparkovers occur, causing damage, possibly irreparable, to the device or installation concerned. The arc heat may also damage plastic components resulting in leakage of cooling water.
These surge voltages occur, for example, in the case of phase-to-ground faults or potential differences in the system, or as a result of system impedances in connection with the high switching gradients of e.g. IGBT semiconductor switches. Apart from sparkovers, these surges may also cause damage to parts insulated to ground (e.g. decomposition or electrical corrosion).
The surge arresters recommended above feature a defect display. It is advisable to perform a visual check on the devices at regular intervals.
Circuit-breaker
Circuit-breaker
Surge arrester
Common rectifier or
rectifier/regenerating unit
Inverter
M
Surge arresters can be ordered from:
Order-No.: 901000 / Type VAV1000
DEHN+SÖHNE Hans-Dehn-Straße 1 D-92318 Neumarkt/Opf.
eMail: info@dehn.de
3-2 | ENGLISH | Siemens AG 6SE7086-4AH85-1BA0 |
| Common rectifier and rectifier/regenerating units with water cooling | Supplement to the operating instructions |
