SMA RA100T-NR - Manual (Page 8)

Assembly and Electrical Connection SMA Solar Technology AG
8 RA100TNR-IEN083510 Installation Guide
4 Assembly and Electrical Connection
The irradiation and temperature sensor RA100T can be connected to the Sunny Boy Control Plus or
the Sunny Central. Observe the prefabricated cable length of 5 m. The cable must not be shortened.
If the length of the cable is insufficient, you can extend it using a junction box, for example. The
temperature sensor can then be connected in either a 2- or 4-cable system.
4.1 Cabling Recommendations
The cable length and quality have an effect on the signal quality. To achieve a good quality signal,
observe the following instructions regarding cabling:
Outdoors
For the outdoors, use a communication cable with the following key properties.
• Cross-section: min. 6 x 0.25 mm
2
, min. 6 x AWG 24
• UV-resistant
We recommend the following cable types:
• UL-listed Lapp cable: UNITRONIC Li9Y11Y 8 x 0.25 mm
2
, order no.: 7038 868
2-cable system
When connecting the temperature sensor in a
2-cable system, the cable resistance is included
in the measurement. This can lead to measuring
inaccuracies depending on the cable length.
For this reason, the 2-cable system should only be used with short cable lengths (max. 3 m)
or where the level of measuring accuracy required is not as high. In order to increase the
measuring accuracy, the use of a 4-cable system is recommended.
4-cable system
To offset measuring errors that occur due to
cable resistance, connect the temperature
sensor in a 4-cable system. With this type of
connection, the current feed and voltage
measurement are carried out by separate pair cables. The length of the cable must not
exceed 30 m.
Protect connection interfaces against weather effects.
When extending the sensor cable, protect the connection interface against weather effects
(e.g. using a junction box or terminal box).