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The detailed set-up of the 4-20mA is described below

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Digital Volt-Free-Contact Interface

Where a fault repeater exists, up to 12 digital outputs may be provided to indicate which sub-feeder is experiencing the worst insulation resistance. These are wired as per standard digital inputs:

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Additional alarm state changes may also be observed, but not if no fault condition exists.

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Real Time Digital Screen:

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This screen is a poor indicator of connection status, as the state of the digital channels depends on the fault condition of the cables under test. Bender CONN DN should be clear.

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Real Time Analogue Screen:

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This should show the present alarm levels, as well as the current resistance to earth reading obtained from the isometer. The value of the Bender Insulation channel must match the value displayed on the isometer display exactly.

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Info
titleTrouble Shooting

If no RS485 data is visible:

  • Be patient. isometers may take up to 2 minutes to complete a single measurement, therefore it may be up to two minutes before data is visible
  • Check the integrity of the wiring. It could be poorly terminated cable.
  • Check the polarity of the wiring. It is very easy to get the "A" and "B" the wrong way around
  • Check for data on the RS485 bus. Ideally use a serial port on a computer to check for traffic. The baud rate is 9,600 bps. You should a string of numbers being transmitted periodically
  • Check for data on the RS485 bus. Alternatively connect a volt-meter with a rapid response across the A and B links. a brief spike in voltage should be observed when data is present on the bus,  Bear in mind the low update rate, and that the RS485 message only lasts a few milliseconds.



4-20mA Setup

You will need to apply a polynomial mapping to translate the 4-20mA output from the Bender RK170 into a readable resistance.

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Simply click on the "name" field in the web-based configuration tool to rename the digital channels such that they match the feeder name (e.g UP, DOWN, BRANCH etc)

DIGITAL SCREEN SHOTImage Added

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Acquiring and Transmitting Data

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Use a simple absolute acquire on Change. Double-Click on each of the Bender ALARM1 and Bender ALARM2 channels in turn and enter the setting shown below:


CONFIG OF ALARM LEVELSImage Added



All Digital Channels

Simply select push-to-server for all physical and RS485 channels. This is achieved by ensuring the "Push to Server" tick-box is checked for digital channels you which to send to Centrix, as shown below

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Live Insulation Resistance (4-20 mA or RS485)

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1) Open the "Rail Events" Tab - This is where we can create all sorts of clever acquisition rules.


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2) Create a new "Rail Event" - This sets up a new set of acquisition rules. It is OK for your Rail Event to errors at this stage.

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3) Create the "Start Trigger" - We want to acquire data when the SA380TX boots up, and then whenever there is a significant change in insulation resistance. Whenever there is a +/-5% change in insulation resistance, a new acquisition is started. It is OK for your Rail Event to errors at this stage.

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4) Tell the SA380TX what to Acquire - We want to keep acquiring insulation resistance values so long as they continue change. Every time the insulation resistance changes by another 5% of its prior value, we grab another sample. It is OK for your Rail Event to errors at this stage.

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5) Set the end conditions - We don't need an "end trigger" we keep on acquiring samples so long as they continue to change. At some point though we want to barrel these samples up and send them to Centrix. This is why we put a time-out period of 1 minute in place.

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Your Rail Event should now have no errors.

END TRIGGER


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Info

Always remember to set the config on the SA380TX before closing the web-page!

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