Transformer Turns Ratio Meter Uses; Limitations Of Turns Ratio Testing - Raytech TR–Mark III 250V Instruction Manual

3.4.3 Transformer Turns Ratio Meter uses:

Transformer Turns Ratio Meter is very useful as a tool for investigating problems associated
with the core, the windings, and the tap changer of transformers and should be used for:
1. Identify shorted turns and finding turn errors
2. Defective and incorrect tap settings
3. Finding mislabelled terminals and mislabelled nameplates
Turns Ratio testing is a required test during the manufacture of transformers.
Turns Ratio testing is a part of a good routine preventative maintenance program as well as
for Acceptance testing.

3.4.4 Limitations of Turns Ratio Testing:

In general, there are few limitations on ratio testing of Transformers. However, there are
limitations to be aware of when attempting to test the following transformer:

Phase relationships other than 30°

Non symmetrical Zig Zag windings

Off-center neutral points

Suspected broken, damaged, or missing core laminations.
In the cases listed above, Raytech recommends the use of the optional unit; model T-Rex, in
conjunction with the TR-Mark III 250V. To get further Information on the T-Rex please view
the website; www.raytechusa.com or contact Raytech to get additional details and
information.
Also, a current transformer is nothing more than an opposite wound voltage transformer.
Most current transformers can be tested with the TR-Mark III 250V.
Please see chapter 'A.A Current Transformer Testing' for details about CT testing.
You may find it difficult to use the TR-Mark III 250V with some low power current
transformers. In this case, please contact Raytech for information about a TR-1.
Instruction Manual TR-Mark III 250V Version 1.10 Preliminary Page 8 of 57