TH2883 Series Operation Manual Chapter 7 User guide
7-4
Both Area size comparison and corona comparison can be used to test coils of motor,
solenoid and relay. Area size comparison, according to energy dissipation, can effectively
detect layer-to-layer short and circle-to-circle short, while corona comparison is mainly
applied to detect coil’s internal insulation failure. If it is required to test inductance,
differential area comparison should be selected.
7.4.3 Settings of comparison method
Sample the standard wave by ways mentioned in 7.2.2 and turn on the required comparisons
dealt with in 7.4.2. For area size comparison and corona comparison, the setting values are
determined by the two methods discussed below:
A.
①
If the condition is permitted, test10 to 20 samples.
②
Find out the entity that has the largest deviation value and then use it to make
electrical test. If this one is good, enlarge the value by 20% and take it as the criteria
(except corona).
③
When testing a product, if a boundary value is detected, repeat step
②
.
④
The corona value is the transition one. The default value is 10.
B.
①
I t is the same as A
①
.
②
Take a coil to make failure test. Short two adjacent turns of coil and then make
another test.
③
Take the differential area size of the sample as the high limit, the maximum unit
differential area size of the sample as the low limit. Select an appropriate value as the
criteria.
④
If the low limit is larger than the high limit, take the product that has the largest
unit difference to make electrical test thus judging whether it is a poor product.
Another way is to average samples (see 7.4.4) to take their differential area size or
switch off the test method and directly take the corona comparison method.
⑤
It is the same as A
④
.
7.4.4 Select standards
1.
Set test voltage. Then observe the corona value under non-standard test mode (7.2.1).
2.
Sample the standard wave by methods mentioned in 7.2.2. Test 10 to 20 samples and
select products that have the most similar differences.
3.
Take the selected products to make sample average (5.3.1 Manual) and choose the final
result as the standard wave.
4.
Results obtaining after procedures 1-3 can be taken as the standards.
7.4.5 Chart for differential area
In the process of BDV test, the secondary display zone displays not only the extraction
