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  • Loop powered 4-20mA input
  • <1V drop across input terminals
  • ± 0.01mA accuracy at 20°C
  • Can be added to existing loop without re-certification
  • Field and panel mounting versions
  • Choice of case material
  • 5-1/2 digit LCD display, 26mm height (process value); Eleven 8mm digits (process units & current)
  • Standard unit location: Zone 0, IIC, T4 hazardous area
  • Zone 2 IP65 certified versions available
  • Backlight options
  • Fully programmable by user
  • Password protected
  • Mounting accessories


The MTL660 indicators are intrinsically safe, loop powered units. The low voltage drop across their input terminals allows them to be installed in almost any 2-wire, 4-20mA loop. Available with a range of styles and options, all MTL660 units can indicate measured values in a linear or a square root extraction mode; the latter being used, for example, to display flow from differential pressure measurement devices such as orifice plates, Dall tubes, or venturi.

The MTL660 digital indicators enable process variables to be displayed locally in hazardous and general purpose plant areas. A typical example would be the re-transmission of mass/flow computations from the safe area, through a suitable MTL IS interface to the indicator in the hazardous area. All models utilize large liquid crystal displays that makes the process variables easily visible at a distance. Process units are configured into the display area. Instant readout of percentage or loop current is available at the push of a button.

The MTL660 is available in four base models. The MTL661 is a field mounted unit housed in a tough aluminum enclosure, suitable for wall or pipe mounting. The MTL662 features the same rugged aluminum enclosure optimized for panel mounting. For corrosive atmospheres, the MTL663 incorporates field mounting with a plastic case that provides excellent resistance to harmful contaminants. The MTL661, MTL662 and MTL663 all feature enclosures measuring 120mm (H) x 130mm (W). The MTL665 is the panel mounted version with an aluminum case and is IP65, IP66, IP67 and NEMA4 rated. The MTL665 measures 72mm (H) x 144mm (W).

MTL660 intrinsically safe indicators are classified as ‘non-energy storing' simple apparatus so they can be inserted into any IS loop without recertification. For Zone 2 mounting, without the need for an IS barrier or isolator, the MTL661-NA and MTL662-NA are available.