Page 202 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

DC generators- power stage

Losses in a dc generator
• Losses in dc machines appear as heat.
• They raise the temperature of the machine.

• Losses also lower the efficiency of the machine.
• Losses include:
1 Copper losses.
2 Iron losses.
3 Mechanical losses
COPPER LOSSES

• Occur due to currents in the various windings.
• Armature copper loss = Ia Ra
2
• Field copper loss = I R or V I sh
2
f
sh
• Also P = Series field copper loss = I se R se
2
Magnetic loss or core loss
• Occur in the armature core of a dc machine.
• Types: Hysteresis & Eddy current loss.

189

CITS : Power - Electrician & Wireman - Lesson 30-37