Baker D30R, User'S Manual & Operating Instructions

Page: 59 / 142

D30R Users Manual
59
Do Not Touch Test Leads while test is in Progress!
71-023 Rev C 5/8/2007
Step Voltage Test
Another test that can be performed using the Digital tester is the Step-Voltage
test. This test is used to indicate the condition of winding insulation by
observing the linearity of leakage current as voltage is increased in steps. The
best results can be achieved if historical records are maintained of multiple Step-
Voltage tests, beginning with measurements made when the winding is new.
Use the same voltage increments and time intervals for all Step-Voltage tests of
a particular winding. Baker Instrument Company recommends that results are
plotted on graph paper in order to make comparisons of different tests.
Note:
It is important for the insulation to be free of moisture and dirt when this
test is made.
Step Voltage Test Procedure
Determine the number of steps to perform, and the voltages and time increments
that best suits testing needs.
For example, if the maximum voltage should be 12,000 volts, it may be best to
use six steps of 2000 volts. The time interval will depend on the capacitance of
the test piece and the type of insulation it uses. Choose an interval that lets a
noticeable change in resistance readings occur at each step. One minute step
intervals are fairly standard or many windings (See IEEE 95 for more
information).
For example, with a 12 kV test instrument:
1.
Connect motor as usual for a HiPot test.
2.
Move Function Knob to 100uA/div position.
3.
Press start button and ramp voltage up to 2000 volts.
4.
Move Function Knob to the best uA/div range for the observed leakage
current.
5.
At one minute, note resistance reading.