Tuesday, April 1, 2014

Electrical Explosion proof Equipment's Standards & Classification

Flameproof Material Standards All Flameproof Electrical Equipment's are Designed and Constructed in Accordance with following Standards:-

àIS 2148-1981
àIEC 60079-1
àIS 13346-1992

A No. of Logical steps are involved in selection of Electrical Equipment for Hazardous Area:-

Step 1:- Identify its Gas Group & Temperature Class
Step 2:- Identify the Zone Area Zone 0, 1 or 2
Step 3:- Select the type of Protection Appropriate to the Zone
Step 4:- For the given type of protection select the equipment keeping in Mind the Gas Group and Temperature rating.
Step 5:- Depending upon whether the Equipment to be installed indoor or Outdoor ensure the correct IP for the equipment

 Apparatus Marking normally include a certification code which include the following:-
Symbol for the type of protection. The apparatus group. The Temperature classification

Example:- Ex ‘d’ IIB T5 This indicates a unit having Flameproof protection of type ‘d’ Suitable for gas group IIA & IIB and having maximum temp. classification of 100 deg. Cel.
As per (T5) Some construction features of this flame proof AC motors are as follows :-
1. The flame proof construction for Exd.
2. The degree of protection is IP 55 for motor main enclosures.
3. The stator winding are of class F insulation and gives a large margin of safety in temperature rise and long service life.
4. The stator winding insulation is good in electrical and mechanical properties, moisture resistance and thermal stability.
5. A cylindrical shaft extension is furnished on motors that can be driven by coupling or spur gearing
6. The rotors are of cast- aluminum and dynamically balanced to make the motor operate smoothly with small vibration and the low noise.
7. Fans are made of cast iron, and have low windage loss.

8. The stator and rotor cores are laminated with high class electrical steel with high permeability and the low loss