Installing and putting a SINAUT modem into operation
5.6 LTOP line transformer with overvoltage protection
Station control system
220 System Manual, 07/2009, C79000-G8976-C178-07
5.6.1 Structure
The protection concept
The protection concept involves a combination of components whose functions supplement
each other:
● Overvoltage suppressors filled with inert gas providing protection against high voltage
(G1, G2)
● Inductors that limit the rise in current (L1, L2)
● Metal oxide varistors as fine protection (voltage dependent resistance; R1)
● Transformer for electrical isolation (T1)
● Suppressor diode to limit the secondary voltage of the transformer (V1)
*
*
/
/
7
5
9
'HGLFDWHGOLQH 0RGHP
Figure 5-23 Circuit diagram of an LTOP unit
230
230
7
/ /
/
/
7
;
;
6
6
;
;
Figure 5-24 Location of the circuit elements of an LTOP 2 (view from above)
Note
The protection elements in the OPM (Overvoltage Protection Module) undergo high stress
during discharge processes and progressively deteriorate. It is therefore recommended that
you replace the OPMs approximately once a year. To be on the safe side, in regions with
frequent thunderstorms this period should be reduced to approximately 6 months.
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