If your fan motor is a 120V, it will most likely have four colored wires (black, blue, red, yellow, etc. When an electric current flows though the wire, a magnetic field is induced inside the coil of wire. Electric motors can be tested to see if there is a short, or open condition within the motor windings which would indicate that the motor is faulty. Step 2. Best practices test the winding path to ground. 2) Place both instrument test leads to ground and verify a solid connection to ground of the instrument lead. 4. Armature Test #1 To check the condition of the armature windings, the armature will probably have to be removed from the motor. Check for proper control signal entering the motor from the 24v field wiring or boards. Check the windings. An electrical induction motor contains windings, or wire wrapped around a cylindrical shaft. The fan speed selections and programming will vary by manufacturer but the intent is to see if there is a proper control input signal. The slot on stator core of the three-phase motor winding carries stator winding. So look for a smaller gauge wire and trace the connections via the up to speed switch. How to Check the Motor Winding Resistance by William Hirsch Updated March 16, 2018. multimeter image by dinostock from Fotolia.com. Also, motors under testing must be disconnected and isolated for proper observation — a key aspect of a full motor winding analysis. If windings are shorted together, the electro-magnetic fields cannot be created for that coil, causing the motor to run erratically or fail all together. To do this, you’ll have to measure the ohms. The most common failure mode of a 3 phase AC motor is burnt winding or shorted winding leading to the damage of the motor. to the motor enclosure. AC Motor Winding Resistance Test Check the motor winding resistance or ohms reading with a multimeter. This can be a bit a challenging and is the primary purpose of the TECInspect tool. Check that the correct voltage is applied to the motor. This test provides a DC voltage to the motor winding and measures how much current flows through the insulation to ground: 1) Test the motor de-energized by using a properly working voltmeter. For proper motor operation, all windings must have megohm readings to ground, i.e. This winding can be supplied with 3-phase AC supply. Next, check the windings of the fan motor for an open or a short. ), as well as a … Often it is required to test the winding of the 3 phase windings with the aid of a multimeter or ohmmeter to determine whether the motor is still good or burnt or shorted. The start winding is usually made of smaller gauge wire and is connected via a centrifugal switch which opens the circuit when the motor is nearly up to speed. The motor winding in three-phase which is connected in star or delta form based on the type of starting method used. Lap winding; Wave Winding; Stator Winding. Power Supply Test For single phase motors, the expected voltage is about 230V or 208V depending whether you are using the UK or America voltage system. If a winding is grounded out, the winding insulation is broken down or the armature is touching the stator, unless there is a possibility of a loose or chafing wire inside.