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Changing the units on the display screen of an ION meter. Is it possible to disable the Auto-Scaling Feature?

Goals and Symptoms

Many people would like to know if there is a way to show Amps and Volts rather than Kilo Amps and Kilo volts on the display screen of an ION meter. There are two ways of doing it, but both processes have pros and cons.

Causes and Fixes

Option 1:
If the primary ratio on the CT or PT is less than 1000, the values are not scaled where as if they are more than 1000 they are scaled. This is called auto-scaling. The firmware decides that since the turn ratio is 1000, the Kilo prefix should appear with the values. The same principle applies for Mega Values, as well.

For Example:
PT Primary = 1000 Volts is not scaled
PT Primary = 1001 Volts is scaled
CT Primary = 1000 Amps is not scaled
CT Primary = 1001 Amps is scaled

There is no way of disabling the auto-scaling feature. For instance, if a 4000:5 ratio is used on the CTs and Kilo Amps units appear, however it is preferable to see amps, the solution is to change the ratio to 800:1 in which case the primary value is less than 1000 and the ratio is maintained.

Note: If the value for the current goes over 1000 Amp than the units will change from Amp to Kilo Amps.

Option 2:
Connect the outputs of the power meter module to an arithmetic module, where the input = output, and pass the required values (Voltage, Current etc.) through the arithmetic module. The values on the output of the arithmetic module can then be linked where necessary, such as the display module or ION Enterprise Vista diagrams.

Note: Auto scaling can be avoided with this procedure however the units such as A, V, kA, kV will be lost for parameters that go through the arithmetic module and are eventually displayed on the screen.


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Date Created: August 10, 2009
Last Revised: August 19, 2009
Original Author: SN
All content © 1992-2009 Schneider Electric

Legacy KB System (APS) Data: RESL199651 V1.0, Originally authored by MiNe on 08/19/2009, Last Edited by MiNe on 08/19/2009
Related ranges: ION7300, ION7550/ION7650, ION8600
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