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4 votes
1- Find the change in the BACK E.M.F when the applied voltage on

D.C shunt motor = 250 volts and armature resistance = 2 ohms and
armature current on full load =40 ampers. and on no load = 10
ampers.

User Superior
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1 Answer

5 votes

Answer: -60v

Step-by-step explanation:

As the given parameters are:

Applied voltage on DC shunt motor (V) = 250V

Armature resistance (R) = 2Ω

Armature current on full load (I1) = 40A

Armature current on no load (I2) = 10A

The back EMF (E) of a DC shunt motor can be calculated using the formula:

E = V - I * R

where V is the applied voltage, I is the armature current and R is the armature resistance.

When the motor is on full load, the armature current is I1 = 40A, so the back EMF can be calculated as:

E1 = V - I1 * R

E1 = 250V - 40A * 2Ω

E1 = 250V - 80V

E1 = 170V

When the motor is on no load, the armature current is I2 = 10A, so the back EMF can be calculated as:

E2 = V - I2 * R

E2 = 250V - 10A * 2Ω

E2 = 250V - 20V

E2 = 230V

Therefore, the change in the back EMF when the motor goes from full load to no load is:

ΔE = E1 - E2

ΔE = 170V - 230V

ΔE = -60V

Hence, the change in the back EMF when the applied voltage on the DC shunt motor is 250 volts, armature resistance is 2 ohms, armature current on full load is 40 ampers, and on no load 10 ampers are -60V.

User Ben Rogmans
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8.0k points