User's Manual

INSTALLATION

FIXED STATIONS

ENVOY™ TRANSCEIVER REFERENCE MANUAL 375

An adequate earthing system is necessary for:

• electrical safety

• static drain

• noise reduction

Related links:

Wiring techniques on page 373

Static drain

In some cases, wind-driven particles, such as dry sand, may charge the transceiver and

ancillaries to very high voltages above earth. Usually the low-impedance protective

earth connection prevents high voltages from building up. In the event that the

protective earth is disconnected or does not exist, as for a solar-powered fixed

installation, these high voltages may occur.

If the voltage of the electrostatic charge becomes sufficiently high, a flashover could

occur between the charged parts and earth. The energy released at flashover depends

upon the voltage of the charged parts to earth. This energy generates a steep wave

front, which may cause failure in the front end of the transceiver or result in damage

elsewhere.

WARNING: A flashover may result in the failure of the basic insulation of a

mains-energised transceiver supply, causing an extreme safety hazard.

To avoid a flashover, ensure that the transceiver is correctly earthed.

Noise reduction

In some cases, noise can be reduced by connecting the case of the transceiver directly

to earth. If an improvement is noticed, the existing functional RF earth may be

inadequate and need improvement.

Where the antenna and transceiver must be installed in close proximity, directly

earthing the transceiver may be necessary to eliminate RF feedback.