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Zener Barrier

£288.00 (inc VAT: £345.60)

Low Stock

SKU: MTL7728+ Category: Brand:


Model MTL7728+ is an intrinsically safe, zone-powered, Zener-diode barrier for use in conventional fire detection systems for protection within hazardous areas. Each Zone contains two stages of pulse-tested 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. A fuse protects the diodes, and the two stages of voltage limitation ensure continued safety if either stage should fail. No active output-current limiting circuits are employed. Model MTL7728+ is certified ‘ia’ for all zones and ‘IIC’ for all explosive atmospheres.


  • Simple installation onto standard DIN railing
  • Removable colour-coded terminals for easy connection, accommodate conductors up to 2.5 mm2
  • Supports up to two zones of I.S. products
  • Input circuitry protected against reverse polarity
  • Can be used with the IFD-E(IS) industrial IR3 flame detector


  • Maximum voltage of Zener diode when fuse blows: ZG-100N
  • Supply Voltage: 28 V
  • Minimum value of terminating resistor : 300 
  • Maximum short-circuit current : 93 mA
  • Number of Channels: 2
  • Maximum end-to-end resistance: 333 
  • Working Voltage: 25.9 V
  • Maximum Voltage: 26.5 V
  • Fuse Rating (continuous): 50 mA
  • Operating Temperature Range: -20 ï‚°C to + 60 ï‚°C (continuous working)
  • Storage Temperature Range: -40 ï‚°C to + 80 ï‚°C
  • Maximum Humidity: 95%RH – Non Condensing (at 40 ï‚°C)
  • Weight (g) / Dimensions (mm): 140 / H90 x W105 x D12.6
  • Mounting Method: DX070 Box, SMB-2 or SMB-3 Enclosures


Additional information

Weight 1.5 kg