Baker D30R User Manual - page 31
High Voltage DC Testing
12/3/2009 | 71-022 V6
D30R
31
General user notices
−
Do not change the test lead select (TLS) switch while a test is being made. Doing so will
cause arcing and damage of the instrument’s components.
−
Do not switch the function control between Surge and HiPot settings during testing.
−
When increasing the applied voltage during a test, use a higher Volts/Div setting so the
entire trace stays visible on the screen. It is acceptable to change this setting while
testing. The Volts/Div control has no effect on and does not limit the output voltage of
the tester. It only controls the display scale.
−
When removing Test Leads ALWAYS unclip the test leads. Do not jerk or pull them from
the motor leads.
−
Only touch the test leads with the Test Lead Select Switch in the ground position.
−
Never connect test leads from two or more testers on the same motor. This includes
connection of host and power pack unit leads to the same motor. This warning also
includes lead connections, even for grounding purposes.
−
Do not connect both the resistance test leads and the high voltage test leads to the
motor at the same time.
High voltage DC test checklist
DC testing
As explained earlier in Chapter 2, the Megohm test gives a quantitative measure of insulation
resistance (IR) and is performed at a test voltage similar to operating voltage of the motor
(See IEEE 43). The PI test gives a quantitative measure of the ability of insulation to polarize.
The PI test is performed at the same time and test voltage as the Megohm test. A DA test is
often done if it is evident that the PI test does not provide useful information or is too long.
The DA test is often called an abbreviated PI test and is described in industry standards
documents that deal with PI testing. The DC over voltage test or DC HiPot, is done to prove
that insulation has the dielectric strength to withstand typical over voltages that a motor can
see while in service due to transients, lightening strikes, loss of a phase, etc. The Baker DR
Series digital testers are capable of performing all described tests during the same application
of voltage to the motor.
Full DC testing of a motor
A Full DC Test of a motor consists of a Megohm, DA, PI and DC HiPot test. Follow the
procedure below:
1)
Connect appropriate high voltage leads to stator windings.
2)
Move Test Lead selector switch to HiPot position.