3.4.16 LBAL - Longitudinal Balance
The longitudinal balance test is Voltech's preferred method to measure what is effectively the Common Mode Rejection Ratio of a transformer designed to connect to a balanced line. Two measurements are performed each by applying a voltage to the transformer and measuring the resulting voltage to calculate the CMRR.
This test is suitable for audio & telecommunication transformers and checks the effective common mode rejection ratio of the transformer.
On selecting "LBAL Longitudinal Balance" from the available tests window, a dialogue box will be displayed:
To program the test:
- Enter the voltage and frequency parameters of the test signal.
(If in doubt, refer to Chapter 7 - ‘Test Conditions’, which lists recommended test conditions.)
Note also that the Measure button may be used here as outlined in section 3.9.
- Select the integration time you require.
'Medium' is the default setting. 'Long' will give more stable readings (for tighter limits) at the expense of an increased test time, and 'Short' will test at the maximum speed, but may give a slightly noisier reading.
- Enter the names of the Hi and Lo input terminals and Common Terminal.
- Enter the names of the Hi and Lo output terminals.
- Set the longitudinal balance limits.
||Enter a nominal value and then the limits as negative and positive
||Enter minimum and maximum values.
||Enter just a minimum value.
- Select OK. The test specification will then be displayed in the program window.