CERTIFICATION

MTL7000 Series barriers protect devices located in all normally

occurring explosive atmospheres, including air/flammable gas

mixtures, dusts and fibres.  MTL7000 Series barriers are certified [EEx

ia] IIC (except MTL7129P+, certified IIB) BY BASEEFA to CENELEC

standards, by FM in the USA, CSA in Canada and also by other

authorities, providing worldwide certification. MTL7000 Series

barriers are designed to the same safety descriptions as MTL700

Series equivalents (in some cases slightly stricter) and can therefore be

used for the same applications.

HOW THEY WORK

All MTL7000 Series barriers are based on the same simple principle.

Each channel contains three stages of Zener or forward-connected

diodes and an ‘infallible’ terminating resistor. In the event of an

electrical fault in the safe area, the diodes limit the voltage that can

reach the hazardous area and the resistor limits the current: active

output-current limiting circuits are not used. An internal fuse protects

the diodes, and the three stages of voltage limitation ensure continued

safety if the first or second stage should fail. MTL7100 barriers have

an additional replaceable fuse which protects the internal fuse.

The MTL7000 Series includes seven key barrier types which cover the

majority of applications, simplifying barrier selection and the

maintenance of spares stocks.