• Range of ATEX Certified intrinsically safe surge protectors
  • Ultra-slim space-saving design; easy installation
  • Multistage hybrid protection circuitry – 20kA maximum surge current
  • Range of voltage ratings – to suit all process I/O applications
  • High bandwidth, low resistance, RTD, PSTN and 3-wire transmitter versions available
  • 10 year product warranty


The MTL SD is a series of surge protection devices combining unparalleled packing densities, application versatility, proven reliable hybrid circuitry, simple installation and optional ‘loop disconnect' facilities – features which make the range the ultimate surge protection solution for process equipment, I/O systems and communications networks. The exceptionally high packing densities are the consequence of an ultra slim ‘footprint' for individual modules which can thus ‘double-up' as feedback terminals. Each module provides full hybrid surge protection for 2 and 3 wire loop protection.

The MTL SD surge protectors are available in 7V, 16V, 32V and 55V and are suitable for a wide range of applications including THCs, 4-20mA loops, shut-down systems and fire and gas detectors. The optional ‘loop disconnect' feature provides both fused protection against fault currents and a convenient method of isolating field circuitry from protected circuitry without needing additional disconnect terminals.

The MTL SD is also available in models specifically designed to meet the requirements for high speed data links with an extremely high bandwidth. These units are available in a range of voltage variants enabling a wide range of communication systems to be protected e.g. RS232, RS422, RS485, Bus powered systems etc. These devices are classed as simple apparatus and can therefore be used in hazardous areas without affecting the certification of the circuit.

For three wire applications, the specially designed SDRTD (Resistance Temperature Detector) and the SD32T3, (for separately powered 4-20mA loops) provide full 3-wire protection in a single compact unit. This range of SD surge protectors offer excellent levels of protection over all three wires in conjunction with minimal footprint requirements. This is the most compact 3-wire surge protector on the market.

In Stock

Part Number Price Available
$225.00 35 in stock
$282.00 28 in stock
$251.00 15 in stock
$273.00 3 in stock

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