O P E R A T O R M A N U A L
23
PERFORMING SPECIAL OPERATIONS
The following section contains information on the care and upkeep of your new VLF SERIES AC Hipot.
There are some notes on troubleshooting and service, which will save much time and money over the life
of the unit.
Meter Re-calibration
The VLF SERIES of AC hipots uses precision metal film resistors for measurement and calibration of the
voltmeter. The use of these resistors in both the high voltage tank and the metering circuits has
minimized circuit drift due to aging and temperature. But, a potentiometer (R4) on the voltmeter PCB can
be used to correct for movement changes from the aging of the meter.
The certification of meters on a yearly basis is recommended to ensure accurate
test results.
Voltmeter Re-calibration
1.
Locate the unit in a position that will allow easy reading of the meters.
2.
Remove the panel screws and support the panel vertically to gain access to the calibration
pot on the back of the voltmeter.
3.
Zero the meter movement using the zero adjustment below the scale window.
4.
Perform the steps in Setting up the Equipment at the start of SECTION 2. Be sure to
ground power section and high voltage tank to a solid earth ground prior to connecting the
unit to input power.
5.
Connect the output cable to a calibrated reference meter with ability to read to the full output
voltage of the unit. Be sure to ground the low side of the meter.
6.
Raise the output to one half scale on the unit meter. Adjust R4 as required.
SECTION
3