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# Series lamp on dc circuits

#### Gaber Mohamed Boraey

##### Full Member level 3
Hello everyone

I think we all know this diagram , we use for safety issues if there is short circuit, so nothing get damage or if damage don’t get bigger

I’m working daily on ups products, ups work on different batteries capacity, starting from one battery to up to 20 for single phase

Let’s assume I only need safety for single phase products, as 3 phase they have breaker

Do you have any ideas about that?

Yes being a resistive load, bulbs are a natural choice for testing, and provide a visual cue telling voltage is present and level of Ampere flow. There are times I have wished for an easy way to hook up two or more bulbs (sometimes in series, sometimes parallel). Example, start with one bulb to test with low Amperes, then test with more bulbs. It would require several lamp sockets (a few in series, a few in parallel).

Since an empty socket doesn't pass current, we could screw in fuses in empty sockets, to remove wherever we wish to place a bulb.

Yes being a resistive load, bulbs are a natural choice for testing, and provide a visual cue telling voltage is present and level of Ampere flow. There are times I have wished for an easy way to hook up two or more bulbs (sometimes in series, sometimes parallel). Example, start with one bulb to test with low Amperes, then test with more bulbs. It would require several lamp sockets (a few in series, a few in parallel).

Since an empty socket doesn't pass current, we could screw in fuses in empty sockets, to remove wherever we wish to place a bulb.
That In Dc circuits?

Hi,

I´m an electronics designer .. thus my idea is to design it using electronic parts.

What does a bulb do:
* it´s rather low ohmic when cold
* on rising current the voltage drop rises
* the result is rising power dissipation
* the result is rising heat
* the result is rising resistance

So if a bulb is not flexible enough for your needs ... I don´t see a problem using a couple of diodes, transitors, capacitors, resistors, potentiometers ... to make the behaviour adjustable.

But like with every design: it starts with requirements and specifications. Values with units.

Klaus

So if a bulb is not flexible enough for your needs ... I don´t see a problem using a couple of diodes, transitors, capacitors, resistors, potentiometers ... to make the behaviour adjustable.
What the name of the circuit design?, what to search for?

Hi,

just kidding.

Maybe call it "current limiter". Or "electronic PTC".

It depends on what function you need. (requirements, values)

Klaus

A cold tungsten bulb will initially pass 10 times as much current in the 1st cycle before it heats up. This is not enough to blow a fuse rated for the bulb.
Thus it makes a good power limiter but not a surge current limiter.