doble SFRA, User Manual, Page: 25 / 126

72A-2570-01 Rev. K 07/2011 3-1
3. Setting Up and Running a Test
This chapter describes how to set up hardware and configure software for
testing and run the test. It also describes typical test results. This chapter
contains the following sections:
• “Measurement Types” on page 3-1
• “Step 1: Set Up and Run a Shorted-lead Test” on page 3-2
• “Step 2: Ground the Transformer” on page 3-12
• “Step 3: Prepare the Transformer for Testing” on page 3-14
• “Step 4: Select and Run a Test” on page 3-15
• “Sample Test Results” on page 3-25
Measurement Types
Open Circuit
An open-circuit measurement is made from one end of a winding to another,
with all other winding terminals floating. For a delta winding, connections
would be H1 to H3, for example. For a star (wye) winding, measurements are
taken from HV terminals to neutral, such as X1 to X0.
Short Circuit
A short-circuit measurement is made with the same SFRA test lead
connections as an open-circuit measurement, but with the difference that
another winding is short- circuited. To ensure repeatability, Doble
recommends that the three voltage terminals on the shorted winding be shorted
together. This would mean, for example, shorting X1 to X2, X2 to X3, and X3
to X1. This ensures that all three phases are similarly shorted, ensuring a
consistent impedance.
Do not include in the shorting process any neutral
connections available for the shorted winding.