In simple words, motor rotation is the result of changing phases in motor windings where the magnetic field alternates between the N and S polarities so that attraction and repulsion forces cause the motor to run. Ensuring good quality of the motor is also relevant to the dynamic power of an electrical vehicle. Motor quality is ensured by tests with Impulse/Surge testers and Hipot testers.
The Microtest Motor Tester Series is mainly for performing “static tests” which measure electrical properties of the motor when the motor is not energized. Motors are made of enamel insulated wire windings. The test parameters and tested properties are similar to that of an inductor. Test items of windings elements include layered short-circuits, insulation voltage, inductance and DC resistance.
Beside of motor test product, Microtest also offer you many related electric vehicle test solution product, such as:
2. Versatile form factors
3. High safety demand
4. High precision demand
5. High quality (lifespan) demand
1. Inductance and resistance testing of windings
2. Micro-short-circuit or short-circuit tests between adjacent layers in the winding
3. Hipot test or safety rating test of the windings and armature
The motors of future Electrical Vehicles will tend to focus on high-price and high quality products. For motor inductance tests, additional measurements of frequency, voltage, and inductance are required, therefore the 6420 LCR Meter comes into the picture. Inductance measurement is performed with an AC signal. Although the 691X has built-in functionality for resistance measurement, it provides a DC signal only. That is why an LCR Meter is necessary.
The Microtest motor testing system including all the R&D, product design and process devising, is the result of a seamless internal teamwork from scratch. The product is now widely recognized by major manufacturers. We continuously strive to expand the footprint of our company.
The Microtest 691X Series Motor Tester mainly measures layered short-circuit and DC resistance.
In recent years, quality issue have been a main concern and enamel insulated wires have shown material mixture problems, therefore layered short-circuit testing has become more and more important. Layered short-circuit testing mainly provides consistency during the motor manufacturing process by comparing wave forms. Whether for the existence of a short-circuit in the respective windings, the number of loops in the winding, the density of winding, quality of the enamel insulated wire, or for any bruise of the enamel insulated wire during the assembly, a layered short-circuit test can give the answer.
Wave comparison items of a Microtest Motor Testing System:
1. Total area comparison
2. Differential area comparison
3. Wave comparison
Motor tests generally use “total area comparison” and “differential area comparison” for waveform comparison. All of these are for testing layered short-circuits, the difference is the allowable tolerance for a layered short-circuit: Total area comparison is the most loose one. Due to yield considerations and process reasons, not all the test items are used.
The principle of a layered short-circuit is that a transient high-voltage impulse is injected into the motor winding in order for the internal capacitance and the motor coil to generate an oscillating waveform (LC charge/discharge characteristic).
In early times, motors were only tested for DC resistance (DCR) without testing inductance, therefore the 691X Series only has built-in DCR testing. With the emergence of micro DCR specifications in recent years, the built-in DCR can no longer satisfy test requirements, therefore Microtest introduced the 691X L, the series for testing micro resistance values (Micro-ohm meter).
Although test systems are 691X+6905+6420, all the controls and settings are accomplished with 691X.
All electrical components require testing for insulation voltage. Theoretically motor windings are isolated from the external, however a leak current will occur as long as a voltage is input. A voltage withstand test is carried out by inputting a high voltage and verifying if the insulation voltage is within safety specification. Voltage withstand is normally expressed in mA (milliamperes) and MΩ, mainly for measuring the extent of insulation between each winding and silicon steel sheets or the casing. In addition to testing insulation of products, the major cause for the voltage withstand test is to meet specifications of international electrical safety codes so that motor products can readily comply with their certification requirements; in this, hipot test is an inevitable link.