Setting Up Tests
39
If the system is to perform a check on the deviation of the results from the nominal turns ratio, it is necessary to enter
values for the “
HV Nom Voltage
” (the boilerplate voltage for the side connected using the ‘H’ cables) and the “
LV
Nom Voltage
” (the boiler plate voltage for the side connected using the ‘X’ cables). This allows the instrument to
calculate how far the measured turns ratio deviates from the ideal value. It is also necessary to enter the maximum
allowable deviation from that nominal ratio in terms of percentage. This is set using the “
Max Deviation
” parameter.
Setting up a Transformer with Regularly Spaced Taps
A transformer with regularly spaced taps is a transformer where the output voltages on the various taps differ by the
same amount between adjacent taps. This is found in applications such as a tap changer type voltage stabilizer
where each tap provides a specific amount of adjustment from the nominal value. If the taps are not equally spaced
see the next section for details.
To indicate to the system that it is testing a tapped transformer, the “
Total Taps
” field is set to a value > 1 . The
value to be set is the number of all outputs. To set up the transformer it is necessary to set up the “
HV Nom
Voltage
” and the “
LV Nom Voltage
” - this sets the voltages for the nominal output. It is then necessary to set up
the number of the bottom tap (“
Bot Tap Number
”) and the number of the nominal tap (“
Nom Tap Number
”) The
way these are set up depends on the “
Tap Numbering
” option in the Options screen. The numbering can be set up
as alphabetic (a, b, C, D...) or numeric (-1, 0, 1, 2, 3). It is also necessary to set up the step between each tap (“
Step
Tap to Tap
”). This is either in terms of an actual voltage step or as a percentage of the nominal value. This is
selected using the Options screen.
If checking of the deviation of the tap from ideal is required, the “
Max Deviation
” value should be set. If you are not
interested in the tap voltage appearing on the test report, it is only necessary to set the “
Total Taps
” parameter.
Example 1
A transformer with 9 equally spaced taps, numbered 1 to 9. The nominal output is the middle one. Each tap gives an
adjustment of 100V, with a nominal output voltage of 1kV from a 6.6KV primary thus
TAP
Primary
Voltage
Secondary
Voltage
1
6.6kV
0.6kV
2
6.6kV
0.7kV
3
6.6kV
0.8kV
4
6.6kV
0.9kV
5 (nominal)
6.6kV
1kV
6
6.6kV
1.1kV
7
6.6kV
1.2kV
8
6.6kV
1.3kV
9
6.6kV
1.4kV
Using Tap stepping entered in percentage set:
“HV Nom Voltage”
= 6.6kV
“HV Nom Voltage”
= 1KV
“Total Taps”
= 9 (Nominal output plus 8 additional)
“Bot Tap Number”
= 1
“Nom Tap Number”
= 5
“Tap Setup”
= LV
“Step Tap to Tap”
= 10%
Using Tap stepping entered in voltage set:
“HV Nom Voltage”
= 6.6kV
“HV Nom Voltage”
= 1KV
“Total Taps”
= 9 (Nominal output plus 8 additional)
“Bot Tap Number”
= 1
Summary of Contents for TTR 2795
Page 1: ...Operating Instructions HAEFELY TEST AG TTR 2795 Transformer Turns Ratio Meter Version 1 4 ...
Page 10: ...6 Introduction Maximum Roll Diameter Outer 50mm Inner 10mm ...
Page 22: ...18 Connection and Setup Figure 11 Connecting to three phase BCT ...
Page 101: ...Application Software APSW 2795 97 ...
Page 111: ...Miscellaneous 107 14 7 Conformity ...