|Equipment and systems covered by this certificate are as follows:|
The DigiTrace NGC-20-CL-E Heat-Tracing Temperature Control Unit with Intelligent Safety Limiter, rated at 100V to 250V and up to 25A, comprises a plastic enclosure into which are encapsulated a number of printed circuit boards. Termination facilities are provided within the enclosure, above the level of the encapsulation, for the connection of power supply, external RTDs, alarm and data transmission facilities.
The encapsulated parts are divided into intrinsically safe and non-intrinsically safe printed circuit boards, with correspondingly segregated Ex ib and Exe termination facilities above the encapsulant.
Internal connections provided from the encapsulated printed circuit boards for three external resistance temperature detectors (RTDs), are made to Ex ib (RTD) terminals situated at the other side of the enclosure, and are segregated from the non-intrinsically safe terminals. Internal connections from the encapsulated printed circuit boards supply a seven segment LED display, five indicator LEDs and two internal push button switches, all mounted on a separate unencapsulated display printed circuit board behind a window in the lid of the enclosure. A common Earth Terminal is provided adjacent to the Ex ib (RTD) terminals for the termination of cable screens.
External connection is provided via cable entry holes, which enter the enclosure above the level of the encapsulation. Internal and external earthing facilities are provided. For Safety Parameters, see Annex.
The safety temperature limiter function of the DigiTrace NGC-20-CL-E meets the requirements of IEC 61508-1:1998 and IEC 61508-2:2003, Certificate Number Baseefa08SR0134.
Omission of the safety temperature limiter function and associated circuitry to form the DigiTrace NGC-20-C-E Heat-Tracing Temperature Control Unit.
The temperature control function of the DigiTrace NGC-20-C-E has not been assessed to the requirements of IEC 61508-1:1998 and IEC 61508-2:2003
|CONDITIONS OF CERTIFICATION: YES as shown below:|
1. Cable entry devices shall be suitably certified and maintain the IP66 minimum of the enclosure. Unused cable entries must be filled with suitably certified stopping plugs.
2. Not more than one single or multiple strand wiring lead shall be connected into either side of the terminals.
3. Leads connected to the terminals shall be insulated for the appropriate voltage and this insulation shall extend to within 1mm of the metal of the terminal throat.
4. When used in dust atmospheres any dust layers occurring shall have a maximum depth of no greater than 50mm.
5. The max permitted current of the Non IS alarm contacts is 3A.
6. The earth pillar adjacent to the RTD connectors must be used only for RTD cable screens.
7. The external RTDs must be capable of withstanding a 500V test to earth.