FORMULA FOR CALCULATING WEIGHTS AND RESISTANCES @ 20C
PHYSICAL CONSTANTS @ 20C
INSULATION CLASSES

FORMULA FOR CALCULATING WEIGHTS AND RESISTANCES @ 20C


FORMULA FOR CALCULATING WEIGHTS AND
RESISTANCES@20C
  COPPER
Weight
kg/km
 
8.8897xa
Length:
m/kg
 
112.5066
a
Resistance:
ohm/km
 
17.2417
a
ohm/kg 1.93975
a
= nominal cross sectional area of wire in square millimeters

 


PHYSICAL CONSTANTS @ 20C

PHYSICAL CONSTANTS @ 20C
PROPERTY ANNEALED
COPPER
Volume electrical conductivity
minimum percent I.A.C.S.
 
100.0
Density:
kg/m
 
8888.4
Weight resistivity:
ohm-mm/m
 
17.2417x10-
Volume resistivity:
micro-ohm-mm
 
17.2417
Temperature coefficient
of resistance; ohm/C
 
.00393
Specific heat; cal/gm/C .092
Coefficient of thermal
conductivity
cal/sec/cm/cm/C
 
 
.934
Coefficient of linear
expansion/C
 
.0000168

INSULATION CLASSES

Insulating materials are classified according to IEC standards into insulating classes showing the corresponding maximum working temperatures that must not be exceeded at any point of the winding. The table below outlines the recognised insulation classifications.

Class
Temperature
°C
Insulating materials
Y
90
Paper not impregnated
A
105
Paper if impregnated
E
120
Polyvinyl Formel - Polyurethane enamels
B
130
Fibre-glass impregnated - Modified polyurethane enamels
F
155
Fibre-glass impregnated in polyester and epoxy resins - Modified polyurethane enamels
H
180
Polyesterimide enamels - Fibre-glass impregnated in class H varnishes
C
200
NOMEX* Fibre-glass impregnated in silicon resins. Polyamide - imide enamels.
220
KAPTON*

* Du Pont De Nemours & Co USA trade mark.