IS 15652/IS 11171

IS: 15652-2006

1.     Insulating Rubber Mat

•  Four classes of mats, covered under this standard nd differing in electrical characteristics for different use voltages are designated
• Class A      AC (Rms)KV=3.3      DC(V)  =240  Thickness =2.0mm         
•  Class B      AC (Rms)KV=11      DC(V)  =240  Thickness =2.5mm    
• Class C      AC (Rms)KV=33      DC(V)  =240  Thickness =3.0mm 
• Class D      AC (Rms)KV=66      DC(V)  =240  Thickness =3.5mm      

 

• Most of all classes hall be resistant to acid and oil and low temperature and shall be identified by the respective class symbol. However a category with special property of resistance to extreme ‘low’  ternperature will be identified by a subscript’s ‘to, the ‘respective “c” Class symbol.
• Roll of Mat shall be in multiple Length of of 5000mm and ion width of 1000mm.Standard Shape in length of 1000, 2000, 3000mm.
• Lockage current for all Class of Mat shall not be more than 10 Micro Amp.
• In Case of Mat in Roll It shall be min 1m X 1m.

 

IS: 11171-1985

2.     TRANSFORMER Cooling Method indication

• Type of cooling Medium: A=Air, G=Gas. Type of Circulation : N=Natural, F=Forced
• First Letter= Type of Cooling Medium (Contact with Winding), 
• Second Letter = Kind of Circulation(Contact with Winding),                                                                                            
• Third Letter= Type of Cooling Medium (Contact with external cooling System),                                                                                    
• Forth Letter = Kind of Circulation (Contact with external cooling System),

3.     TRANSFORMER Temperature Rise Limit

• Part                                  Type of Insulation                Degree.Centigrate                                                                                          
• Part=Winding       Type of Insulation=A        Degree.Centigrate=50
• Part=Winding       Type of Insulation=E       Degree.Centigrate=65
• Part=Winding       Type of Insulation=B        Degree.Centigrate=70
• Part=Winding       Type of Insulation=F        Degree.Centigrate=90
• Part=Winding       Type of Insulation=H        Degree.Centigrate=115
• Part=Winding       Type of Insulation=G        Degree.Centigrate=140
• Part=Core, Metalic Part       Type of Insulation=-        Degree.Centigrate= Not rise to damage core or metallic part.                

4.     TRANSFORMER Reduce Temperature Rise Limit

• TRANSFORMER designed for operation at an altitude greater than 1 000 m but tested at normal altitudes  the limits of temperature rise are reduced by the following amounts for each 500 m by which the intended working altitude exceeds 1000Meter                                                                                                                                                         
• ( a) Natural-air-cooled Transformers 2.5 %  (b) Forced-air-cooled Transformers %

5.     TRANSFORMER Parallel operation Condition

• (1 )Rated power ( kVA );                                                                                                                                                     
• (2) Rated voltage ratio;                                                                                                                                                       
• (3) Voltage ratios corresponding to tappings other than the principal tapping.                                                          
• (4) Rated power ( kVA ); Rated voltage ratio; Voltage ratios corresponding to tappings other than the principal tapping.                                                                                                                                                                  
•  (5) Load loss at rated current on the principal tapping, corrected to the appropriate reference temperature.                                                                                                                                                             
•  (6) Impedance voltage at rated current ( on the principal tapping ).                                                                             
• (7) Short-circuit impedances, at least on the extreme tappings, if the tapping. Range of the tapped winding exceeds + or – 5 %.