System Details; System Check; Transformer Turns Ratio Testing - Raytech TR–Mark III 250V Instruction Manual

3.4 System Details

3.4.1 System Check:

The instrument is Line operated. The system is designed to be used with voltage power
sources (mains power) between 100-250 Vac 50/60Hz. The system performs a self-check
each time that it is powered on. The User should always visually inspect all connectors,
cables and devices to be measured to avoid any safety issues.

3.4.2 Transformer Turns Ratio Testing:

A Transformer Turns Ratio Meter does exactly as its name implies; it is used primarily for
checking the ratio of Turns of wires of the primary side and the secondary side of a
transformer. The Turns Ratio test set does not tell exactly how many turns of wire are in the
primary and secondary coils. But rather, it measures and displays the Ratio of (or
comparison of) the number turns in the primary coil to the number of turns in the secondary
coil.
This is an extremely useful device for checking for shorted turns and incorrect settings of tap
changers. The TR-Mark III 250V has an additional feature of allowing the operator to
measure the actual phase angle and vector relationship of the windings.
It is important to understand that the Nameplate Ratio on most transformers is the Voltage
ratio (Voltage in: Voltage out) and this Ratio is determined, basically, by the number of turns
of wire on the Primary (High side), the number of turns of wire on the Secondary (Low Side).
On a single phase Transformer the Turns Ratio is the same as the Voltage Ratio.
A Single Phase transformer:
For example: The High Side Winding may contain 940 Turns: Low Side Winding 440 Turns.

TurnsRatio
Therefore:
With three (3) Phase Transformers of different configurations, the Turns Ratio & Voltage
Ratio can, and usually is different.
NOTE
 The TR-Mark III 250V makes all the calculations and interconnections
required when the correct configurations of single (1) phase and
three (3) phase transformers are selected. In most cases, no other
external connections, other than the test leads provided, are required.
Refer to: Section 1: Safety Precautions for safety grounding.
 Hooking up to a transformer:
The TR-Mark III 250V protects against a wrong hook-up to a
transformer or testing a severely defective transformer. Every effort
has been made to alert the operator when something is wrong.
 Negative (reverse polarity) hook up is also automatically detected.
Instruction Manual TR-Mark III 250V
H1
H2
Pr imaryTurns
940

Sencondary Turns 440
Version 1.10 Preliminary
X1
X2

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