SAFETY REQUIRMENTS & ADVICE SHEET (continued)
Adherence to BS 7671, Chapter 42 (Protection Against Thermal Effects), and in particular;
420.3 –General Requirements,
421 –Protection Against Fire Caused by Electrical Equipment
o421.1
o412.2
422 –Precautions Where Particular Risks of Fire Exist
o422.1.2
o422.1.3
should be undertaken, and as a minimum, a mains isolation switch, a load-breaker switch and a contact breaker should be installed in the electric heater
battery controller supply. The supply to the contactor coil should be interrupted by an over-temperature (hi-limit) thermostat located in the heater battery
and also upon detection of airflow loss (fan proving), via an air flow switch, air DP switch across the fan or fan current switch in the fan supply.
Additionally, EN 61508-1:2010 (Functional safety of electrical/electronic/ programmable electronic safety-related systems. General requirements)
stipulates the general requirements for electrical, electronic and programmable electronic safety devices, and covers the safety systems of electrical
equipment and their components that could have an impact on the safety of people and the environment if they fail. BS EN 61508-1 also applies to
protection and control systems, and helps organisations to identify hazards to improve overall equipment safety in the workplace.
Failure to incorporate these safety interlocks may result in the invalidation of fire insurance, building and contents insurance, and in extreme cases may
result in the disconnection of the electrical supply by the distributor.
Operation, Installation & Configuration
The RE-3P has been designed to control electric heating loads in proportion to the incoming, selectable analogue signal. Control of the load is facilitated by
the use of solid-state semiconductor devices and feature zero crossing point switching of the AC load which virtually eliminates RFI problems.
Caution
In normal operation the heat sink surface can exceed 90°C. Dangerous voltages exist on the PCB and particular care should be taken. RE-3P must be
installed in accordance with the relevant statutory regulations and installation must be carried out by an experienced and fully qualified engineer.
Ventilation
The RE-3P is suitable for use up to a maximum ambient temperature of 45°C which should not be exceeded. If necessary, enclosures or control panels
should be ventilated with a cooling fan, particularly if the unit is being used to run at full power to provide forced cool air movement over the heat sink.
Over Temperature Monitoring
The RE-3P is provided with an electronic thermal cut-out fitted to the heat sink to protect against over temperature. The unit will switch off the load if the
heat sink temperature exceeds 95°C and will automatically reconnect the load once the heat sink temperature has dropped below 85°C. Upon switching,
the alarm output from the control PCB will change from 24V to 0V.
The heat sink temperature will not reach 95°C under normal operating conditions. However, this might occur if the ambient temperature exceeds 45°C.
The RE-3P is suitable mounting on DIN Rail and must be installed with the heat sink cooling fins orientated vertically. There should be a minimum of
100mm vertically between units.
Electrical Installation
Installation must be carried out by a suitably trained electrician, and in accordance with the relevant statutory regulations.
Load Supply and Back-up Protection
High speed fuses or miniature circuit breakers should be utilised to provide back-up protection to the switching devices. It is recommended that a load
disconnect switch and a contactor are installed in the load supply. The supply to the contactor coil should be interrupted by an over-temperature
thermostat located in the heater battery and also upon detection of airflow loss.
