The document discusses terminal voltage calculations for a generator. It provides the formulas for terminal voltage (V), generated emf (E), and armature current (Ia). It then works through an example where the load current is 100A, terminal voltage is initially 200V but increases to 210V due to cable resistance. It determines the field current is 4.2A, armature current is 104.2A, and generated emf is 214.17V.

1. Terminal Voltage

4. !

5. Terminal Voltage
V = E - IaRa

6. Generated emf
E = V - IaRa

7. I = If + IL
from Kirchhoff ’s current law

8. E = Generated emf
V = Terminal voltage
Ra = Armature resistance
Ia = Armature current
IL = Load current
If = Field Current (I = V)
Rf

10. !
Load current (IL) =
20 kW =
20,000
= 100 A
200 V
200

11. !
Volt drop in the cable to the load
= IL x RC
= 100 (100 x10ˉ³) = 10 V
Hence terminal voltage = 200 + 10 = 210 V

12. !
Field current (If) =
V =
210 =
4.2 A
Rf
50

13. !
Armature current (Ia) = If + IL = 4.2 = 100 = 104.2 A

14. !
Generated emf
(E) = V + IaRa
210 + (104.2 x 40 x10ˉ³)
210 + 4.168 = 214.17 Volts.