1
1  INTRODUCTION
This instruction manual describes the procedures for installing, connecting, checking and 
maintaining MTL5500 range of isolating interfaces and accessories. The MTL5500 products provide 
a DIN-rail mounted, intrinsically safe interface to hazardous areas of a process plant.
The individual sections of this manual cover the following topics
• 
Section 2 describes the range
•  Section 3 specifies precautions both before and during installation
•  Section 4 describes mounting accessories and the power adaptor
•  Section 5 discusses the DX range of enclosures
•  Section 6 provides relevant technical data
•  Section 7 outlines fault-finding and maintenance procedures
•  Section 8 describes bench test procedure
•  Section 9 provides hazardous-area application information
•  Section 10 provides MTL5000 products information
•  Section 11 provides safety parameter information
2  DESCRIPTION
MTL5500 
range of
 isolators provide intrinsically safe (IS) communication and signal conditioning 
for a wide range of hazardous-area devices. Total AC and DC isolation exists between input, 
output and power supply on separately powered units, and between input and output on 
loop-powered units. No IS earth is required. DIN-rail mounting and plug-in signal and power 
connectors simplify installation and maintenance. Units are powered from a 20 to 35V DC 
supply, or, in some cases, from the signal itself.
Our latest generation of IS interfaces utilises an innovative “One-Core” technology to ensure 
the highest quality and availability while maintaining maximum flexibility at lowest cost. 
Incorporating advanced circuit design, a common set of components and innovative isolating 
transformer construction, they achieve a significant reduction in power consumption while 
increasing channel packing densities. The compact, 16mm wide design reduces weight and 
gives exceptionally high packing density. They build on the proven success of the MTL2000, 
3000, 4000 and 5000 ranges to bring the benefits of new developments in galvanic isolation 
without compromising the reliability of the designs from which they have evolved.
The backplane mounting MTL4500 
range
 is designed with system vendors in mind for “project-
focussed” applications such as Distributed Control System (DCS), Emergency Shutdown 
Systems (ESD) and Fire and Gas monitoring (F&G).
The DIN-rail mounting MTL5500 range meets the needs of the IS interface market for 
“application focussed” projects, ranging from single instrument loops, through to fully equipped 
cabinets, across all industries where hazardous areas exist.
Both new ranges have been designed for compatibility with earlier models. The MTL4500 range 
provides plug-replacements for earlier MTL4000 range of units, while the MTL5500 models 
can easily replace MTL5000 
range of
 units. Each offer the latest in modern technology and 
efficiency without compromise.
In addition to their use in IS circuits, specific models within the MTL4500 and MTL5500 
ranges have been assessed and approved for use in Functional Safety applications. These 
have been verified under the certified Functional Safety Management (FSM) programme 
implemented by us.