ElectricalAge
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Electrical-Age
[Potential Oversight] Component failure with Negative Voltages
Some electrical components will fail in the presence of a negative voltage, and in most cases it can easily be explained as an internal diode blowing due to reverse bias. However there is absolutely no logical reason why a relay should fail when a negative voltage is present. I believe this to be an over-looking as the block can be placed backwards with no ill effects, yet a negative voltage does affect it.
I'm a bit more shaky on this one but the voltage probes will fail in negative voltage. I'm not sure if that's because an internal component requires a positive voltage to function or if this is another case of voltage direction affecting something it should not.
Re-branded this as a lot of machines will flat-out fail if given a negative voltage even if there's no reason for it to fail in its presence:
Heaters: Shouldn't care at all which direction the electricity is coming from Motor-Based Machines: If given a negative voltage should simply spin the opposite direction Lights: Dependent on the bulb. LEDs should snap while the other bulbs work normally
There is also a bug in the GUI where the voltage meter's bar will dip below 0 as a result of negative voltage.
That's an issue. Propably because (for example) 200v components have voltage rating 0-200v. Giving it -50 is techicly overvolting them, but they shall handle that fine. But i don't think negative voltage is as usefull in DC anyway.
In most cases it's not, but when dealing with capacitors negative voltages go all sorts of places you don't want them and it makes it very difficult to work around when all forms of controller feint at the sight of a negative voltage.
I can rectify a reverse-facing current with a full bridge, but I can't do any meaningful manipulation of a negative voltage nor is there anything I can build which can allow for that either.
How exacly did you generate negative voltage? Just used power source? Or is there any other way?
Capacitors produce negative voltages on the opposing side when you charge them. If you put it straight to a ground it won't cause issues but if you need to check the current coming from the ground you're SOL.
Bumping this again. Diodes will fail to draw current at all if the voltage is negative, even if a current should be allowed due to the positive voltage difference. If placed backwards, the diodes will allow the flow.
Once again, another error. Hubs when given a negative voltage will fail.
I Have also had issues with negative voltages appearing in some of my Generator current limiting circuits which are used for starting Gen-Sets (By using resistor / DC converter stages, switched by relays to prevent overloading cables), once the engine start and all the relays are opened, sometimes they / the "floating" parts of the circuit they are connected to somehow go into negative voltage and cause explosions. The only way i have been able to stop this happening is to had additional relays that ground any floating circuits to a ground point when not in use. Not ideal, but its a an ok temporary work around.
I found that a good fix for the time being is to have a useless diode reverse-facing a ground. I'm not sure why it works, but it will help prevent over-undervoltage until the bug is sorted out.
Using diodes to ground is the best way to prevent negative voltage, for the time being. It prevents negative voltage because it can "source" positive potential energy from the ground pin to raise the voltage to zero. Since it's floating, it takes almost no current to do this, and the voltage stays at or above zero volts. The nice thing about diodes is that they are like one way valves - what brings the voltage up will not bring it down. Theoretically, one can place diodes to ground on all/any wires with no ill effects (as long as they are connected correctly)
sent from Jared's phone
On Sun, Jun 17, 2018, 11:29 PM OmegaHaxors [email protected] wrote:
I found that a good fix for the time being is to have a useless diode reverse-facing a ground. I'm not sure why it works, but it will help prevent overvoltage until the bug is sorted out.
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