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Emergency lighting unit blows up if battery of lamp is disconnected...how fix?

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treez

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Emergency lighting unit blows up if battery or lamp is disconnected...how fix?

Hello,

We have a lamp which runs off a current source when the mains is on, this current source drives the LED luminaire, and another current source drives current into the battery to charge it, (battery runs the lamp when mains fails)

The problem comes when the lamp is disconnected when the mains is on, because the current source just keeps being a current source and pushes the rails up to very high voltages which blows it up.

...The same applies to the battery , when the battery is removed the current source keeps flowing but has nowhere to flow into.

It would be good if we could short out the battery and lamp connections in the event of such dicsonnection......then there would be a path for the current to flow.

As such, i wondered if their is such thing as a connector which when disconnected, it leaves a short across the terminals........then when re-connected, it breaks the short.

do you know of such a thing.?
 
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Syncopator

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Replace your current source with a circuit similar to a normal bench power supply. Set the unloaded output voltage and the current limit to convenient values.
 
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FvM

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There are no ideal current sources in real design. A real circuit should be able to handle open terminals by suitable means. There are a few switching connectors available, but possibly not with the voltage/current/isolation rating required by your application.
 

andre_teprom

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Re: Emergency lighting unit blows up if battery or lamp is disconnected...how fix?

If you have access to equipment schematic, could attach a circuit to control stage to limit output voltage.


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treez

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Thanks.

if there are no such connectors (ie, ones which leave a short behind them when disconnected), then i thought of a diac/SCR arrangement whereby the diac breaks over as the voltage rises and turns on the SCR....which conveniently shorts the current from the current source.

Any other ideas please?
 

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I was thinking about a zenner diode arrangement on closed loop control circuit.
However, it is hard to talk about solution without more details about topology used.


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