atlantisburn
Technical User
I have a 750 watt (1400 watt Max) power inverter which kicks the breaker when desktop computer with a 450 watt is connected. I feel this is strange since I can hook up household vaccums with no problem.
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Power Inverter Kicks Breaker
- Thread starter atlantisburn
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franklin97355
Technical User
Power inverter? What happens if you connect directly?
You must have more than an inverter because an inverter assumes some DC to invert.
So you have some sort of UPS. Full time conversion or only when power fails?
What else is on the circuit? What is breaker amperage?
Is it possible that the UPS is under full load charging at the same time the computer is started? If so you could be pulling enough to trip a sensitive breaker.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
So you have some sort of UPS. Full time conversion or only when power fails?
What else is on the circuit? What is breaker amperage?
Is it possible that the UPS is under full load charging at the same time the computer is started? If so you could be pulling enough to trip a sensitive breaker.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
Are you powering the monitor as well as the computer through this invertor? Depending on the type of monitor, it could be the extra power drawn by this device on startup is momentarily exceeding the maximum available.
Could also be that the invertor's power limit is internally set on the mean side...
ROGER - G0AOZ.
Could also be that the invertor's power limit is internally set on the mean side...
ROGER - G0AOZ.
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- #5
atlantisburn
Technical User
Sorry didn't give much detail. I wish to hook a desktop to my vans 12v power via DC to AC inverter. Monitor will be vans existing LCD screen. Inverter should kick breaker at aroung (at least) 700w. I am only using half that. The vacuum I ran on the inverter runs at 5 amps or about 500 watts.
I doubt your Desktop would be drawing 450W continuously, but if we assume it'll draw this as a peak at switch-on (could be more), your invertor needs to pull at least 37Amps at 12v assuming it was 100% efficient! Which it isn't! Say it's 75% efficient in converting 12vdc to 230v AC, you're going to need about 50Amps.
How are you connecting the invertor to the van's electrical system? For that sort of power I suggest you'd need to be using some pretty thick, short cables direct onto the battery terminals.
Have you tried switching on the PC when the vehicle's engine is running, i.e. alternator charging the battery?
ROGER - G0AOZ.
How are you connecting the invertor to the van's electrical system? For that sort of power I suggest you'd need to be using some pretty thick, short cables direct onto the battery terminals.
Have you tried switching on the PC when the vehicle's engine is running, i.e. alternator charging the battery?
ROGER - G0AOZ.
- Thread starter
- #7
atlantisburn
Technical User
Plugs into cigareette lighter or accessory via 10, 12 or 14 gauge wire. Engine is running. So you are saying the is a minimum of amps to pull as well as as max. Next I will try to add other device to inverter a same time I connect computer.
No, don't add any more devices!
What I'm saying is, you're trying to pull a lot of current out of the invertor which probably isn't getting sufficient low voltage input power via the cigarette lighter connection.
When you hit the "ON" button for your computer, the voltage sag through the cigarette lighter connection is probably such that it momentarily drops to maybe 11, 10 or even 9 volts, which in turn means even more current is required to make the invertor produce 230 AC etc.
Sure, your cigarette lighter will draw a hefty current to make the element glow red hot, but there are no electronic circuits in it to throw a wobbly and it doesn't care if the voltage drops to 10v - it'll still get hot enough to ignite the tobacco.
Try connecting the invertor directly onto the vehicle battery terminals - this will ensure you suffer the minimum voltage drop when initially turning on the computer.
You get a similar scenario when starting the vehicle. If you crank the engine over on the starter motor with the lights on, you'll notice they dim appreciably. On a cold morning your 12v battery will maybe drop to 9 or 8 volts because of the huge current drawn by the starter motor.
ROGER - G0AOZ.
What I'm saying is, you're trying to pull a lot of current out of the invertor which probably isn't getting sufficient low voltage input power via the cigarette lighter connection.
When you hit the "ON" button for your computer, the voltage sag through the cigarette lighter connection is probably such that it momentarily drops to maybe 11, 10 or even 9 volts, which in turn means even more current is required to make the invertor produce 230 AC etc.
Sure, your cigarette lighter will draw a hefty current to make the element glow red hot, but there are no electronic circuits in it to throw a wobbly and it doesn't care if the voltage drops to 10v - it'll still get hot enough to ignite the tobacco.
Try connecting the invertor directly onto the vehicle battery terminals - this will ensure you suffer the minimum voltage drop when initially turning on the computer.
You get a similar scenario when starting the vehicle. If you crank the engine over on the starter motor with the lights on, you'll notice they dim appreciably. On a cold morning your 12v battery will maybe drop to 9 or 8 volts because of the huge current drawn by the starter motor.
ROGER - G0AOZ.
You possibly could split the loads within the computer. Smaller power supply to support the M/B and I/O cards and a power regulator to supply the hard drive and floppy off the vam power directly without the double conversion. Drives could be switched on after the switching supply has stabilized.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
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- #11
atlantisburn
Technical User
Remember, inverter will run other electronic devices that pull more amps.
Im not an expert on this stuff, but i was thinking more along the lines of instant demand rather than total demand on the line. Instant demand would be the quick high-power demand that, say, an elegric kettle puts on a line. Im thinking that perhaps the line cant handle the instant demand caused when you start up, or rather perhaps the breaker cant handle the instant demand.
A vaccuum may not put that kind of demand on a line. Just a thought anyway.
I guess G0AOZ is basically saying the same thing, except i am looking at the breaker itself. Breakers wear out and sometimes are prone to click off sooner than they should.
Good advice + great people = tek-tips
A vaccuum may not put that kind of demand on a line. Just a thought anyway.
I guess G0AOZ is basically saying the same thing, except i am looking at the breaker itself. Breakers wear out and sometimes are prone to click off sooner than they should.
Good advice + great people = tek-tips
Other electrical devices (like your vacuum cleaner) won't pull anything like the initial momentary current that a computer switching mode power supply demands. As I suggested previously, maybe the invertor's power limiting circuit is set slightly on the low side. I doubt whether this is easily adjustable though...
Have you tried any other makes/models of computer on this setup?
ROGER - G0AOZ.
Have you tried any other makes/models of computer on this setup?
ROGER - G0AOZ.
I agree that it is with the initial surge, which was the reason for the suggestion to try splitting the loads. High power applications under maximum usage restrictions generally use a phased power up to keep the surgees under some control.
I'm surprised the vacuum didn't pop the breaker. Initial surge there should have been pretty much like a power supply, although I've not ever had reason to compare them with test instruments. But I have fought the battle with motors and sensitive breakers.
You may need to consider a systme with lower power needs, or possibly a laptop as their power requirements are much less. I've had 2 laptops running off of a 135 watt inverter. Granted that they were older systems with lower requirements.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
I'm surprised the vacuum didn't pop the breaker. Initial surge there should have been pretty much like a power supply, although I've not ever had reason to compare them with test instruments. But I have fought the battle with motors and sensitive breakers.
You may need to consider a systme with lower power needs, or possibly a laptop as their power requirements are much less. I've had 2 laptops running off of a 135 watt inverter. Granted that they were older systems with lower requirements.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
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