Siemens SIMATIC NET SINAUT ST7 System Manual page 263

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.
The LTOP variants
The housing contains either one LTOP unit (= LTOP 1) or two LTOP units (= LTOP 2). The
following figures show the design of both LTOP variants with their connectors and
configuration switches.
View from above
X1
X2
X2 + X3
X6
S1 + S2
SINAUT ST7 Station control system - System Manual
System Manual, 05/2007, C79000-G8976-C178-06
Dedicated line (screw terminals 1, 2, 5, 6)
Chassis (screw terminals 3, 4)
Modem attachment 2-wire over screw terminals
Modem attachment 4-wire over screw terminals
2-wire/4-wire modem attachment over RJ-12 Western connector; for direct connection of
the SINAUT ST7 MD2 modem over the standard connecting cable (RJ-12 – RJ-12) that
ships with this modem.
Configuration switches
Installing and putting a SINAUT modem into operation
6.5 LTOP line transformer with overvoltage protection
Schematic
263