1.1 This standard is applicable to rotating motors on electric locomotives or vehicles for railway and road transportation and on the vehicles they drive. These motors are collectively referred to as traction motors in this standard. They include DC (or pulse-current) traction motors, DC and synchronous main generators for electric and thermoelectric locomotives and rolling stock, DC and synchronous motors for driving auxiliary machinery, and DC or synchronous generators and their electric generating units for auxiliary power sources.
1.2 The tests are divided into type test and inspection test, and test items shall be in accordance with JB 3369-83 Basic Technical Conditions of Traction Motors.
1.3 Any test method not specified in this standard shall be agreed between the user and the manufacturer.
2 Preparation before Test
2.1 Selection of measuring instruments
2.1.1 Electrical measuring instruments (except megohm meter) and tachometers with a level of accuracy of not less than 0.5, as well as other measuring instruments with a level of accuracy equivalent to 1.0 shall be used.
2.1.2 The selected measuring range of instruments shall be able to make the measured value within the range of 20% to 95% as far as possible.
2.1.3 When measuring the voltage of winding, the voltmeter shall be connected to the outgoing end of the winding under test. When measuring the current with shunt, the resistance of measuring line shall be selected according to the requirements of the millivoltmeter used.
2.2 Protective measures
During the test, necessary protective measures shall be taken to avoid accidents due to harmful airflow at high temperature, high voltage, high speed and foreign matters that may escape from the motor.
Before the test, the motor assembly quality, bearing operation and brush contact surface shall be checked. All tests specified in this standard can be carried out only if the above factors do not affect the quality of electrical performance test.
2.4 Determination of brush neutral line
Before the test of DC motors, the neutral position of brush shall be corrected according to the follow methods:
a. Induction method: when the armature is stationary and exciter is the other excitation, switch on and off the excitation power source alternately, and gradually move the position of brush to measure the induced potential on the adjacent two sets of brushes. When the induced potential of the armature is close to zero in several positions, the position of brush at this time is the neutral line.
b. Forward or reverse rotation of generator: the motor operates as a generator and moves the position of the brush step by step under the same excitation, speed and load conditions. When the voltage values of the forward and reverse rotation are the closest to each other, the position of brush at this time is the neutral line.
c. Forward or reverse rotation of electric motor: the motor operates as a electric motor and moves the position of the brush step by step under the same excitation, terminal voltage and load conditions. When the speed values of the forward and reverse rotation are the closest to each other, the position of brush at this time is the neutral line.
3 Test Methods
3.1 Measurement of the insulation resistance of winding against housing and between windings
3.1.1 The insulation resistance of winding shall be measured under the following conditions:
a. The winding is in the actual cold state (the temperature difference between the tested winding and the cooling air is no more than 3 K, which can be measured by a temperature variometer).
b. The winding is in thermal condition (generally, it can be measured immediately after temperature rise or load test).
3.1.2 Selection of megohm meter to measure insulation resistance
According to the voltage to earth at rated operation time of the motor, select according to the following provisions:
a. 250 V megohm meter for ground voltage up to 250 V.
