how to test a transformer with a digital multimeter?

To test a transformer with a digital multimeter, first ensure the transformer is disconnected from power. Set the multimeter to the resistance (ohms) setting. Measure the primary winding resistance by connecting the probes to the primary terminals; a low resistance indicates a good winding. Next, measure the secondary winding in the same way. Finally, check for short circuits by measuring resistance between windings and between windings and the core; infinite resistance is ideal.