Thursday, 1 September 2011

Static earthing

The newly upgraded Earth-Rite TELLUS II from Newson Gale offers effective static earth verification for drums, IBCs and other mobile equipment in hazardous area operations. The lightweight static dissipative polyester (SDP) enclosure can be mounted in all industrial flammable or combustible atmospheres and provides the operator with a reassuring bright green flashing LED to confirm a positive connection to earth, as well as a pair of output contacts for interlock with pumps, valves or other control or alarm devices.

The Earth-Rite® TELLUS constantly monitors hazardous area processing operations involving the handling, transporting or mixing of flammable or combustible products, whether they be powders or liquids. Operating in real time, the system confirms that a positive connection to earth exists and, most importantly, remains intact for the duration of the operation. As long as the resistance of the connection to a designated earth exists and remains below 10 ohms a bright green pulsing LED display inside the hazardous area assures the operator of safe conditions, preventing dangerous static electricity accumulation on the monitored object.

Newson Gale selected 10 Ohms as the monitoring threshold for the pass/fail condition as this conforms to all major international industrial static control technical standards and guidelines. The system very accurately monitors to this low resistance and switches from permissive to non permissive whenever the resistance to the earthing point rises above 10 Ohms, or is lost completely. An additional interlock mode (pair of changeover contacts) can provide an extra margin of safety by sounding an audio alarm or initiating an automatic safe shut-down procedure should the earth connection be lost. The Intrinsically Safe Earth-Rite TELLUS Indicator/Junction Box is made from lightweight SDP and is easy to install and observe close to the point of use – for example on drum filling or mixing machines.

The Earth-Rite TELLUS Static Earthing System consists of a power supply unit and controller which is mounted in a safe area as much as 500 metres / 1,600 feet from the hazardous area and, within the hazardous area, the intrinsically safe earth-connection status-indicator with a two-pole earthing clamp on retractable connection cables in various length options. Both the PSU/Controller and Indicator/Junction Box are waterproof and dust-tight (IP66 / Nema 4X). Alternative connections, such as plugs and sockets, are also available. The system operates on 110V – 230V AC (user selectable) 50/60Hz supply, with certified Intrinsically Safe (I.S.) monitoring circuit output for connection in the hazardous area. 

The Earth-Rite TELLUS enables compliance with the best practice guidelines of NFPA 77 and CENELEC TR 50404 for controlling static electricity. All TELLUS monitoring systems are approved for safe use in Hazardous Areas to ATEX “Ex” European/IECEX standards and US and Canadian standards (Class/Division or Class/Zone) for all gas, vapour or dust operating environments. In addition to its hazardous area approvals, the system achieves a SIL 2 Functional Safety rating according to IEC 61508 and has an operational temperature range of -20 to +60 deg C.
For over 25 years, Newson Gale has been supplying the chemical and processing industries worldwide with its market leading range of static control products to help ensure people, plant and processes are protected from static caused fires and explosions. The Earth-Rite TELLUS forms just part of the range of static earthing and bonding equipment available from the Nottingham UK based company.

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