Transformer rectifier: Explosion proof

Transformer rectifiers for zone 1 & 2

Hellas Rectifiers can build transformer rectifier units for Zone 1 & 2 areas according to the 94/9/EC (ATEX) directive. Kema Quality B.V. (No. 0344) has carried out inspections on Hellas units up to 150A and has made the following commentary:

EX II 2 G / Eex od IIB T5

The T/R units can be classified in two ways in the 'new' approach:

Protection Cat. Performance of protection Conditions of operation
High 2 Suitable for normal operations as well as for frequently occurring disturbances or locations where faults normally have to be taken into account. Equipment can be safely operated and functions in Zones 1, 2.
Normal 3 Suitable for normal operations. Equipment can be safely operated and functions in Zone 2.

The surface temperature of the Hellas units will never exceed 90° C (at an ambient temperature of up to 40° C). For this reason the Hellas units cannot ignite flammable gasses and vapours. The Hellas units thus meet the T5 requirements.



Protection Performance of protection
Input 220 .. 480V - 50/60 Hz
  1 or 3ph
Control Manual – 63 step / Variac
  Automatic – Thyristor (Current, voltage and/or potential)
Output Voltage - Up to 100 Volt, (higher consult Hellas)
  Current - Up to 150 Ampere, (higher consult Hellas)
  Ripple – 5% for 63 step 3 phase, (others consult Hellas)
Rating Continue
Protection Overload – MCB or fuses
  Overvoltage – VDR (25 kJ 8/20 µs)
  Lighting – GDT (150 kA 8/20 µs) ‘Optional’
  Temperature – Thermo switch @ oil temp: 80°C
  Liquid level switch
Cooling ONAN
Meter DC – voltage
  DC – current


After 30 June 2003, all transformer rectifiers purchased or put into service will have to conform to directive 94/9/EC. This directive replaces the old directives regarding explosive atmospheres as well as relevant national regulations. Directive 94/9/EC applies for all transformer rectifiers to be installed within the European Community (irrespective of where they are manufactured).