Performing IM tests ; dc test , blocked rotor test & no-load test , to determine the parameters of induction machine.

1. i. DC Test of determination of stator resistance
Connect any two stator leads to a variable-voltage DC power supply.Power supply is adjusted to
provide rated stator current. Then determine the resistance from the applied voltage VDC and
stator current IDC as follows.

2. Then, the AC resistance is given by:
R 1=1.15 RDC
ii. Blocked-Rotor Test
From the DC test, determine R2 when combined
with data. The rotor is blocked so that it will not
turn. A variable-voltage AC supply is connected and
adjust the supply voltage until the blocked-rotor
current is equal to the rated current. Neglect the
exciting current under blocked-rotor conditions to
remove the shunt parameters of equivalent circuit.
Finally determine X1 and X2.
blocked
rotor

3. iii. No-Load Test
The rotor is allowed to run freely under no-load
condition at rated voltage and rated frequency. At no-
load condition, the speed is very close to synchronous
speed and the slip =0, causing the current in R2/s to be
very small, and will be ignored in the calculations.
Determine the magnetizing reactance, XM and friction,
combined core and windage losses.