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Subject: Re: ma meter placement in midpoint of secondary to ground
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Date: 08/08/02 at 12:54 AM
Posted by: Godfrey Loudner
In Reply to: ma meter placement in midpoint of secondary to ground posted by guy ditty on 07/22/02 at 10:32 PM:
I'm not familiar with every x-ray transformer in the world, but I'll explain the set up I know about. Let's suppose your transformer has two high voltage coil sections and the bottoms of each section are directly connected together and grounded to the core or tank of the transformer. Then there would be almost no potential difference between the center connection and ground (hence the microamperes). Maybe this transformer was configured that way because it had only one job to do and no monitoring of the current was necessary. You can monitor current with an mA meter along the x-ray cable route, but that is very awkward. A better way is the following. Don't have the bottoms of the two high voltage sections connected directly together. Break the connection if necessary. Take the lead from the bottom of one high voltage section and connect it directly to the transformer's tank. If possible use a terminal on top the tank that is NOT insulated from the tank. Then take the lead from the bottom of the other high voltage section and connect it to a terminal on top the tank that IS insulated from the tank. This terminal does not have to have any major insulation from the tank. Now you just place the mA meter across the the insulated and uninsulated terminals. If you leave the bottoms of the two high voltage sections connected directly together, no current will flow through the mA meter.
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