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Kelvin Pre-Check Test Option

New Free Feature - Saves Time and Confirms Connection Integrity

Rapid silent check of your connections before test execution removes human error from your results

Over the course of running a large batch of parts, the Kelvin connections to your transformer could potentially become contaminated with debris, varnish or could be just accidentally misaligned on inserting a specific part.

The AT5600 automatic pre-check of your connections provides a quick but useful validation that each component is fitted properly before a test run, which provides the best confidence in the following testing.

This will save users time, as any failure is immediately flagged, and the program run stopped if bad connections are detected. It also stops any accidental false scrap/wastage/investigation that can be caused by bad connections, not the actual part.  It also provides the same check before compensation to make sure the compensation applied (for all later tests in a batch) is not bad, due to accidental bad connections during compensation.

The check is run before every normal test sequence, and is checked before the normal test program sequence even starts.
Hence any accidental bad “false fail” results due to poor connections are not sent to the server.
If a problem is detected, the user then has the chance to correct any bad connections and then resume the test.
The Kelvin Pre-Check does not tell you anything about the actual transformer under test, but does confirm that SOURCE and MEASURE nodes are connected to every pin used in the test.

See AT5600 Editor user manual for full details

What Is Tested ?

Any of the 20 AT nodes connected to a winding, core or screen terminal on the schematic is tested once before every program run.

As the test is a very quick continuity check on each node, you will pay almost no time penalty for enabling the option.

Checks Source + Measure integrity
Checks Source + Measure integrity

How Is A Kelvin Check Performed?

To perform the Kelvin check, each node has the sense line shorted to ground and the power line is energized with a low voltage (this is internal to the unit, the user just has to connect part as normal)

If the connection between the power and sense lines is poor, the easiest path for the current to take is through the current sensing shunt and a large current will be measured.
If the connection is strong, the current sensing shunt will be bypassed, and the measured current will be small.

Any resistance lower than 5 Ohms from source to measure will pass the test, and any resistance higher than 5 Ohms will fail the check. If there are one or more failures, a failure report will be shown which indicates which node number failed and a terminal name that corresponds to that node.

The user can adjust their connections to resolve the issue and retry, ignore the failure and continue with testing, or ignore the failure and abort the testing.
In the case of retry and ignore, the execution is resumed by pressing the RUN button.

example of AT5600 detecting an OPEN cct Kelvin pair on node 15
example of AT5600 detecting an OPEN cct Kelvin pair on node 15

How Do I Enable The Test Option ? - Editor Settings

The AT Editor has three settings for performing the Kelvin Check in the Program options. They are as follows:

Off - This is the default state and what is used for older programs where the Kelvin check state is not specified. In this mode, no Kelvin checks are performed.

Ignore Open - This is a relaxed testing mode which requires the Kelvin check to pass during short circuit compensation, load compensation and test execution. Open circuit compensation will not have a Kelvin check.This mode is recommended if there is only low frequency testing, as you can simply remove the fixture to do open circuit compensation.

All - This mode is a strict testing that will execute the Kelvin check before any compensation or test execution. This mode is recommended to get the best connection reliability.

Configure Transformer Testing
Configure Transformer Testing

Legacy AT Testers (AT3600, ATi)

This test option is not available on the AT3600 or ATi.
However, programs with the Kelvin option enabled can still be used on these products, but the flag will simply be ignored.
This prevents users from maintaining two separate test programs, and maintains ATP program portability between unit type

Contact Us

Any Questions on this feature? Comments?

If you have any questions about the above or would like help upgrading your AT5600 to take advantage of these new features, please contact us for help.