Cable grip and cable specifications, Wiring and terminal block diagrams, E-m-hf7-v1_24 – ROTRONIC HF7 User Manual

Page 12

E-M-HF7-V1_24

Rotronic AG
Bassersdorf, Switzerland

Document code

Unit

HygroFlex HF7 Humidity Temperature
Transmitters: User Guide

Instruction Manual

Document Type

Page 12 of 23

Document title

Lightning protection

Cabling in areas with a risk of lightning requires a lightning protection. For cabling underground in between
buildings, we recommend the use of special fiber optic cables. If this is not possible, use copper cables that
are suitable for underground installation.

6.2 Cable grip and cable specifications

The HF7

is supplied either with one M16 sealing cable grip or with a ½” conduit adapter. The M16 cable grip

provides effective sealing only with cables having the proper outside diameter. Preferably, use a cable with an
outside diameter of 6 to 7 mm (0.236 to 0.275 inch) with 18 AWG wires.

6.3 Wiring and terminal block diagrams

6.3.1

HF72: 2-wire, loop powered transmitter

Electrical diagram

The maximum permissible cable length connecting
the HF72 to other devices is determined by the total
resistance resulting from the addition of the cable
resistance and that of the devices connected in series
with the unit. This resistance should not exceed 500
ohms.