Connection
SMA
Technologie AG
Page 24
SSM-TEN072310
Technical Description
7.4 RS485 and Power Supply Connections
7.4.1 Cable Type for the Data Line
Connection of the RS485 bus and the +55 V DC power supply in the SSM-C is to be
realized by means of a single cable. The corresponding cable type must contain eight
wires as twisted pairs, and have a minimum cross-section of 0.5 mm² (4 x 2 x 0.5 mm²).
This is necessary because the +55 V DC power supply requires four of the cable's
conductors, with two conductors used in parallel in each case, in order to guarantee a
cable cross-section of 1 mm². For communication, however, only two conductors are
required: data + and data -. The remaining two wires are used as reserves.
7.4.2 Shield Contact Connection
The cable shield must be connected to the provided shield rails in the inverter and SSM-
C. The shield clamps can accept cables up to a maximum diameter of 8 mm. Handling
of the shield clamps is pictured below. The shield clamps must only be hand-tightened.
Never use a screwdriver. Screwing the shield clamps with a screwdriver can damage
the insulation.
Information
The cable type Li-2YCYv is recommended!
NOTICE!
Do not screw in the shield clamps with a screwdriver, hand-tighten only!