The MTL SD range 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.

MTL SDX
SDX units, available in 7V, 16V, 32V and 55V versions (SD07X, SD16X, SD32X and SD55X respectively) are suitable for a wide range of applications including THCs, 4-20mA loops, shut-down systems and fire and gas detectors.

MTL SD
In addition to the many beneficial features offered by SDX devices, the SD variants fuse/disconnect package provides both fused protection against fault currents and a convenient method of isolating field circuitry from protected circuitry without needing additional disconnect terminals. Also provided is a third connection on the field and safe side of the protector in order to terminate screens safely to earth.

MTL SDR
The MTL SDR range has been specially designed to meet the requirements for high speed data links with an extremely high bandwidth. SDR 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.

SD32T3, SDRTD, SDR3
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.

The mSA range of surge protection devices is designed to safeguard remote electronic equipment from surges on signal and data cabling. Models are available in a range of working voltages to cover all process-related signals such as RTDs, THCs, 4/20mA loops, telemetry outstations, shut-down systems and fire and gas detection. The weatherproof enclosure of the mSA range is rated at IP65 making it particularly suitable for locations which are regularly exposed to lightning activity and suffer frequent damage. These self-resetting devices continue to protect even after a surge has passed making them maintenance free, again ideal for remote locations. The maximum surge handling capability of the mSA range units is 10kA.

• Ready boxed in weatherproof housing with cable glands
• Range of voltage ratings available to cover all process related signals
• Single and dual pair versions
• Fully auto resetting, maintenance free
• 10 Year 'No Fuss' Warranty

ZoneBarrier modular telecom protection devices provide a uniquely customer configurable port-by-port protection approach. ZoneBarrier modules can be utilised as either stand-alone devices or as building blocks to create an unlimited multi-port protection system. Modules are available in modular jack or terminal strip formats for applications including dial-up, lease line, ISDN and modem protection. ZoneBarrier devices can be wall mounted, DIN rail mounted or mounted on any flat surface in a 19" rack. Other ZoneBarrier modules are available for network and comms applications, further details of which are given in the Network & Comms Protection section of this website.

• High surge current capacity
• Wall, DIN or 19" rack mountable
• Modular jack or terminal strip connectors
• Modules available for a range of telecom applications
• 10 Year 'No Fuss' Warranty

The TP48 surge protection device safeguards field-mounted process transmitters where it matters, right at the unit. After a simple installation (the TP48 screws into an unused conduit entry, with no additional modification), it provides high-level protection against surges and transients whilst normal operation remains unaffected. The TP48 resets itself automatically after each operation. The TP48 is available with screw threads to suit different transmitters, with explosion proof and intrinsically safe options for hazardous areas. Working voltage is 48V dc maximum with impulse ratings of 10kA peak current and 10kV peak voltage.

• Easy and direct mounting - simply screws into spare conduit entry
• Intrinsically safe and flameproof (explosion proof) approved versions
• Range of thread types available
• Fieldbus compatible
• Available in 2, 3 & 4 wire versions
• 10 Year 'No Fuss' Warranty

The TP4/7 surge protection device is a unique unit providing a level of protection for field-mounted transmitters that is far in excess of the optional transient protection facilities available from the transmitter manufacturers - without invloving any additional wiring, conduit modifications or other expensive extras.

• Specifically designed for Multivariable Transmitters and Level Transmitters
• Four wires protected, one pair at 12V to 24V and one pair at 7V (e.g. RS485)
• Easy and direct mounting - simply screws into spare conduit entry
• Intrinsically safe and flameproof to CENELEC standards
• FM, CSA and ATEX approved

The TP-Pipe surge protection device safeguards field-mounted process transmitters where it matters, right at the unit. The TP-Pipe screws directly into the conduit entry, with no additional modification. After this simple installation, it provides high-level protection against surges and transients whilst normal operation remains unaffected. The TP-Pipe resets itself automatically after each operation. The units are available with screw threads to suit different transmitters, with explosion proof and intrinsically safe options for hazardous areas. Working voltage is 48V and 32V dc maximum with impulse ratings of 20kA peak current and 20kV peak voltage.

• Easy and direct mounting - simply screws into spare conduit entry
• Intrinsically safe and flameproof to CENELEC standards
• Low impedance series connection avoids signal degradation of the loop
• ATEX approved
• 10 Year 'No Fuss' Warranty

The HW48 device safeguards Honeywell STT350 intelligent transmitters against surges and transients from field cabling. This Honeywell tested and approved unit fits onto the side of the STT350 transmitter inside the standard 'flameproof'(Ex d) enclosure housing giving a 10kA level of protection. Installation and earthing is simple so even existing installations can easily be upgraded by retrofitting the HW48. Analogue and Smart local current meters can be wired into the transmitter and will benefit from protection provided by the HW48.

• Honeywell tested and approved for use with STT350 transmitters
• Customised mounting for simple installation and wiring
• Analog and smart meter compatible
• Retrofittable - easily fitted to existing installations
• 10 Year 'No Fuss' Warranty

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The multi-stage hybrid of the SLP range uses a combination of solid state electronics and a gas filled discharge tube (GDT) to provide surge protection up to 20kA. The SLP is designed to exhibit exceptionally low line resistance and adds only a tiny voltage drop to the circuit. In operation, the SLP device does not adversely affect the performance or operation of the loop or combined equipment. The device allows signals to pass with very little attenuation while diverting surge currents safely to earth and clamping output voltages to safe levels.

• Surge protection for two loops per SLP (or one 4-wire circuit)
• Space-saving design; 6mm width per loop
• Plug connectors for quick and easy connection
• Multi-stage hybrid protection circuitry; 20kA maximum surge current
• Designed for high bandwidth, low resistance applications
• ATEX Certified intrinsically safe
• 10 Year 'No Fuss' Warranty