- 2073 Magh · 8 marks
Compare DC shunt and series generators
Short answer
Shunt generators have field parallel with armature, many turns of thin wire, voltage drops with load; used for battery charging and lighting. Series generators have field in series, voltage rises then falls; used for boosters and arc lighting.
Make a detail comparison of dc shunt generator and dc series generator with their diagrams, equations and characteristics curve.
A shunt generator has the field winding connected in parallel with the armature, and a series generator has it in series with the armature and the load.
Circuit diagrams
SHUNT SERIES
+--Ia-->--+---> IL +--Ia-->--[Rse]---> IL
| Ra | (G) |
(G) Ish Rsh [LOAD] | [LOAD]
| | | +---------------------+
+---+------+
Equations
- Shunt: I_a = I_L + I_sh; I_sh = V/R_sh; V = E_g − I_aR_a − brush drop; E_g = V + I_aR_a
- Series: I_a = I_se = I_L; V = E_g − I_a(R_a + R_se) − brush drop
Characteristic curves
Shunt V-IL Series V-IL
V|***** V| ****
| *** | ** ***
| ** | *
| * |*
+-----------> IL +-----------> IL
The shunt external characteristic drops slowly, then turns back near the maximum current. The series characteristic starts from the residual voltage, rises with load, then falls after saturation.
Comparison
| Basis | Shunt generator | Series generator |
|---|---|---|
| Field winding | many turns, thin wire, high resistance | few turns, thick wire, low resistance |
| Field connection | parallel with armature | series with armature |
| Field current | I_sh = V/R_sh, almost constant | equals load current |
| Armature current | I_L + I_sh | I_L |
| Voltage build-up | needs no-load start | needs a closed load circuit |
| No-load voltage | full rated voltage | only residual emf |
| V as load increases | decreases slightly | increases then decreases |
| Voltage regulation | fairly good | poor |
| Short-circuit | self-protecting (V and field collapse) | large current, dangerous |
| Uses | lighting, battery charging, excitation | boosters, arc lighting |
✓ Answer checked by Claude Opus 5.5 (high effort)
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