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The following guidelines are derived from the European standard EN 50170 for the transmission of signals by copper wires. Note on installation planning: when determining the position of machinery and equipment, the rules given in EN 50170 should be followed with due regard to local circumstances. Whenever the level of electromagnetic interference is expected to be high, both the instruments and signal cables should be placed as far away as possible from the source of interference. In general, signal cables should be installed in bundles or channels / conduits, separate from other cables as indicated in the table below:
•Bus signals such as RS485 •Data signals for PCs, printers etc. •Shielded analog inputs •Unshielded direct current (<= 60V) •Shielded process signals (<= 25 V) •Unshielded alternate current (<= 25V) •Coaxial cables for CRT monitors |
in common bundles or channels / conduits |
•Direct current from 60 V to 400 V (unshielded) •Alternate current from 25V to 400 V (unshielded) |
in separated bundles or channels / conduits, without minimum distance |
•Direct and alternate current > 400 V (unshielded) •Telephone lines •Lines leading into EX-rated areas |
in separated bundles or channels / conduits, without minimum distance |
Preferably use a shielded cable to connect the analog outputs of the HC2A to other devices. The maximum cable length is determined by the maximum error that the user will accept. This can be calculated as follows:
Error (V) = cable resistance x current through load
Use one of the available connecting cables (see Cables) to connect the UART digital interface of the HC2A probe to other devices. Without a signal booster, the maximum cable length should not exceed 5 m (16 ft).
In the case of a fixed installation, ground the HC2A probe, especially if the electronics will be subjected to a low humidity environment (35 %RH or less). The power supply and digital ground (GND) and the analog ground (AGND) should be tied separately to a proper ground so as to avoid spikes in the analog signals.