In the Quick Start Tutorial (section 3 of chapter 2), it was stated that for the R - Winding Resistance - test the limits could be entered in four different ways. The R test is not unique in this respect. In fact, most tests have several ways in which the limits may be entered, allowing you greater flexibility in configuring each test to match your production testing requirements.

The four types of limits for the R- Winding Resistance - test are:
%:	The limits are entered as positive and negative percentages about a nominal value.
> <:	The limits are entered as minimum and maximum values.
> :	There is only a minimum limit.
< :	There is only a maximum limit.

The corresponding dialogue boxes are as follows:

Many of the tests available for the AT Series have all four limit types. There are obviously some tests where it is not sensible to have four limits, IR - Insulation Resistance - being a clear example where only a minimum limit is applicable, as the perfect insulation between windings has no upper limit to its resistance.

To choose which type of limit you wish to use, simply use the mouse to click on one of the buttons % , > < , > or < .

After you have entered the limits in one form, you may change to another form of limits by clicking with the mouse on another of the buttons.

When you change from one limit type to another, the tester will convert any limits you have previously entered to match the new type as shown in the following tables:

CONVERSION BETWEEN LIMIT TYPES FOR TESTS OTHER THAN TR AND TRL

	Conversion	Previous
%	nom ← (max + min) / 2 \|neg%\| ← (nom - min) / nom pos% ← (max - nom) / nom nom ← low + 0.01% \|neg%\| ← 0.01% pos% ← 0.01% nom ← upp - 0.01% \|neg%\| ← 0.01% pos% ← 0.01%	> < > <
dB +/-	nom dB ← (max dB + min dB) / 2 \|neg dB\| ← nom dB – min dB pos dB ← max dB – nom dB nom dB ← low + 0.01 dB \|neg dB\| ← 0.01 dB pos dB ← 0.01 dB nom dB ← upp - 0.01 dB \|neg dB\| ← 0.01 dB pos dB ← 0.01 dB	> < > <
> <	min ← nom - \|neg%\| max ← nom + pos% min ← nom dB – neg dB max ← nom dB + pos dB min ← low max ← low + 0.02% min ← upp - 0.02% max ← upp	% dB +/- > <
>	low ← nom - \|neg%\| low ← nom dB – neg dB low ← min low ← upp	% dB +/- > < <
<	upp ← nom + pos% upp ← nom dB – neg dB upp ← max upp ← low	% dB > < >

Where:
nom dB neg dB pos dB nom neg% pos% min max low upp	= = = = = = = = = =	the nominal value for the [ dB ] limits the negative error for the [ dB ] limits the positive error for the [ dB ] limits the nominal value for the [ % ] limits the negative percentage error for the [ % ] limits the positive percentage error for the [ % ] limits the minimum value for the [ > < ] limits the maximum value for the [ > < ] limits the minimum value for the [ > ] limit the maximum value for the [ < ] limit

CONVERSION BETWEEN LIMIT TYPES FOR THE TESTS TR AND TRL

New	Conversion	Previous
% neg% pos%	pri ← #np sec ← #ns ← (δnp / #np + δns / #ns) ← (δnp / #np + δns / #ns)	#
# δnp δns	#np ← pri * K #ns ← sec * K ← #np * (\|neg%\| + pos%) / 4 ← #ns * (\|neg%\| + pos%) / 4	%

Where:
pri sec neg% pos% #np #ns δnp δns K	= = = = = = = = =	the primary ratio number for the [ % ] limits the secondary ratio number for the [ % ] limits the negative percentage error for the [ % ] limits the positive percentage error for the [ % ] limits the number of primary turns for the [ # ] limits the number of secondary turns for the [ # ] limits the ± error number of primary turns for the [ # ] limits the ± error number of secondary turns for the [ # ] limits a factor to make #np and #ns whole numbers in the range 1 to 99999

Notes

The conversions in the above tables are written in a form to make it easier for you to understand the conversion process; they are not intended to be exact mathematical formulae.
Some changes in the tables above are not reversible.
For example, after you have changed from a > < limit which has two values to a > limit which has only one, changing back will not give the original values again.
This is because the Editor only holds the latest limit values, and therefore when you have changed to a minimum only limit, any previous maximum value will be lost.
When a single value limit (such as > ) is converted to a multiple value limit (such as > < ), the conversion process has in essence to use the previous single value as both the minimum and maximum new values.
As it is not logical to have a minimum and a maximum exactly the same, the two values are made different, but only by a small amount.

Prev Next