Current Injection Circuit - Electronic Circuits Projects Diagrams Free

Jester009 · 6th September 2007, 07:12 AM

Hi,

I am required to come up with a current injection circuit. The circuit would output user defined currents(preferably use a microcontroller for this purpose) I'm looking for a range of 0A-12A.

Please any input is deeply appreciated, I'm clueless here

Thanks
Jester009

Super_voip · 6th September 2007, 11:31 AM

What is the current being injected into?

What voltage range?

Jester009 · 6th September 2007, 11:41 AM

Hi Super,

Thanks for the reply. This is part of a project I am assigned. If I describe the whole scenario, this is what happens...

Quote:

The user selects the level of current from an interface in the computer. Then the computer communicates wit a circuit and that specified current is injected from the circuit into a relay. The tripping time is sent back to the computer.

I'm talking about the circuit which output that specified current to the relay. Hope I made it clear enough. Current have to be controlled within 0 - 12A

Thanks
Jester009

Super_voip · 6th September 2007, 11:52 AM

So a circuit breaker tester, there would appear to be 3 parts to this
1. Generate the current
2. read the current
3. read the time delay in tripping the breaker

Jester009 · 6th September 2007, 12:21 PM

Yes, Can you shed any light on 'how to generate the current'
I have to complete the project within this month and I have no idea where to start

Thanks

specie · 6th September 2007, 06:05 PM

Is the current 'Alternating' or 'Direct'

Super_voip · 7th September 2007, 10:56 AM

Doesn't matter, circuit breakers will work with either, as for the current try relays switching at, say, 1 Amp levels and transistor-fet to supply at lower levels. So have a bank of relays directing the voltage source through a resistor which will keep the current to desired level to a paralleled output.
A careful selection of currents via the relays will reduce the amount of relays needed eg 1,2,4,5 Amps will give you 0-12Amps in 1 Amp steps except 8amps,so you can see 12 relays aren't needed. The transistor supply will need to be able to supply 0-1A.

**Nigel Goodwin** · 7th September 2007, 11:38 AM

Quote:

Originally Posted by Super_voip

A careful selection of currents via the relays will reduce the amount of relays needed eg 1,2,4,5 Amps will give you 0-12Amps in 1 Amp steps except 8amps.

I think you need to check your binary maths?

1, 2, 4 and 8 amps would make more sense, and give 1A steps from 0 to 15 amps. Even with the 5A you suggested, 8A is simple 5+2+1.

Super_voip · 7th September 2007, 11:42 AM

I wasn't going to work it out for him/her, and I'm tired

specie · 7th September 2007, 01:05 PM

Quote:

Originally Posted by Super_voip

Doesn't matter, circuit breakers will work with either, as for the current try relays switching at, say, 1 Amp levels and transistor-fet to supply at lower levels. So have a bank of relays directing the voltage source through a resistor which will keep the current to desired level to a paralleled output.

What about Thyristors or triacs?

Jester009 · 7th September 2007, 01:12 PM

I have to inject an AC current ranging from 0-5A. Triacs or Thyrisotors do not produce pure sinusoidal waveforms. do they?

specie · 14th September 2007, 08:48 AM

Quote:

Originally Posted by Jester009

I have to inject an AC current ranging from 0-5A. Triacs or Thyrisotors do not produce pure sinusoidal waveforms. do they?

Neither do relays. They are to be used instead of relays

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6th September 2007, 07:12 AM	(permalink)
Jester009	Current Injection Circuit Hi, I am required to come up with a current injection circuit. The circuit would output user defined currents(preferably use a microcontroller for this purpose) I'm looking for a range of 0A-12A. Please any input is deeply appreciated, I'm clueless here Thanks Jester009

6th September 2007, 11:31 AM	(permalink)
Super_voip	What is the current being injected into? What voltage range?

6th September 2007, 11:52 AM	(permalink)
Super_voip	So a circuit breaker tester, there would appear to be 3 parts to this 1. Generate the current 2. read the current 3. read the time delay in tripping the breaker

6th September 2007, 12:21 PM	(permalink)
Jester009	Yes, Can you shed any light on 'how to generate the current' I have to complete the project within this month and I have no idea where to start Thanks

6th September 2007, 06:05 PM	(permalink)
specie	Is the current 'Alternating' or 'Direct'

7th September 2007, 10:56 AM	(permalink)
Super_voip	Doesn't matter, circuit breakers will work with either, as for the current try relays switching at, say, 1 Amp levels and transistor-fet to supply at lower levels. So have a bank of relays directing the voltage source through a resistor which will keep the current to desired level to a paralleled output. A careful selection of currents via the relays will reduce the amount of relays needed eg 1,2,4,5 Amps will give you 0-12Amps in 1 Amp steps except 8amps,so you can see 12 relays aren't needed. The transistor supply will need to be able to supply 0-1A.

7th September 2007, 11:42 AM	(permalink)
Super_voip	I wasn't going to work it out for him/her, and I'm tired

7th September 2007, 01:12 PM	(permalink)
Jester009	I have to inject an AC current ranging from 0-5A. Triacs or Thyrisotors do not produce pure sinusoidal waveforms. do they?