72A-2243-01 Rev. B 9/04 3-1
September 17, 2004
3. Leakage Reactance Test Procedures
Test Considerations
There are two options being offered for measuring leakage reactance using the
M4000. The M4130 Leakage Reactance Module requires the use of an
external user-supplied variac and user-supplied current cables. The M4110
Leakage Reactance Interface includes all controls, cables, and safety
interlocks, and the Leakage Reactance Module in a single package. Following
are instructions for use of the M4110.
In addition to the M4000, it is necessary to have the following equipment for
Leakage Reactance Testing:
• Doble Leakage Reactance Interface, including
• Set of M4110 Voltage Source Cables
• Set of M4110 Voltage Sense Cables
• M4110 Ground Cable
• A set of heavy jumper cables for short-circuiting the Low Voltage
winding
• The M4110 leakage reactance software module for the M4000
If using the M4130 Leakage Reactance Module, a variac and three cables are
required to connect the variac autotransformer to the transformer bushings and
the Leakage Reactance Module. The size of the cable must be in accordance
with the variac rating. Note that the M4130 Leakage Reactance Module is
rated 400 volts, 50 amperes. The M4130 is supplied with voltage sense cables
and a DC power supply cable.
Information Needed Before Running a Test
Although it is possible to run a test without any transformer nameplate
information or benchmark data, % Reactance and % Impedance cannot then be
calculated. Transformer nameplates include the following information which
should be entered into the M4000 program prior to running a test:
• Percent Impedance
• Base VoltAmperes (in MVA) for this impedance
• Base Line-to-Line voltage (in kV) for this impedance
• Tap positions for which the nameplate values were obtained
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