Atec Hiptronics-700 Series - Manual (Page 3)

ACCESSORIES
2820a
& 2840 C / tanδ bridges DDX Series Partial Discharge Detectors
SELECTING AN AC TEST SET
In order to properly size an AC Test Set, it is necessary to have the
following information:
1. Maximum test voltage required The maximum test
voltage is determined by the relevant standard that
equipment is being built to plus any additional user-
defined over sizing to take into account changes to test
standards, or special end-user requirements.
2. The power rating to determine the power rating, the
capacitance, resistance or inductance of the load must be
known. High voltage test objects are usually capacitive in
nature.
3. PD requirements Partial discharge testing is usually
performed at lower levels than AC withstand levels. If PD
testing is required it is necessary to know the PD
sensitivity level for the test and the test voltage.
Specifying too high a PD test voltage or unnecessarily low
PD free rating for the system inflates the cost of a test
system.
4. Environment Most testing is done indoors in reasonable
environments. If the HV test transformer is to be located
outdoor or in a harsh environment, bushing size and tank
design will change.
CURRENT VERSUS CAPACITIVE LOAD
If the load is predominantly capacitive, the test current
required can be calculated by using the following formula:
A = 2  ƒCV
Where:
 A = Test current in Amps
 ƒ = Test frequency in Hertz
 C = Total test load capacitance in Farads
 V = Test voltage in Volts
Once these four things are known, the test voltage and
load current can be used to determine the rating of the
system. We suggest that you consider rating your system
10 to 20% higher in voltage and up to 50% higher in
current to accommodate future, unanticipated test
requirement changes.