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# Tag Info

## Hot answers tagged power-electronics

5

Multiplication of Vrms and Irms gives average power into a resistive load only. Into other loads which result in out of phase waveforms, capacitive, inductive, rectifier for instance, the result is not average power. If you multiply Iavg by Vavg, the caveats are similar. For well behaved waveforms like DC, the result is average power. It's easy however to ...

2

Triacs are nothing like two transistors and a diode. Read the Wikipedia article or (better, I think) the GE SCR manual ca. year 197x which will explain things better than anyone here is likely to spend the time doing. There are four possible quadrants of operation. The commonly shown two-SCR "equivalent" (which would be like four transistors) is also very ...

2

Since you have 6 Li-Ion batteries in series, you could charge them at 25.2V (Since the max charge for a Li-Ion is 4.2V * 6 = 25.2V). The current used the charge the cells depends on the battery itself. Batteries usually have a part number printed on them. So if you find the datasheet, then you can determine the maximum current you can charge the batteries at....

2

You can certainly use a transistor and trigger a triac (or SCR). Typically that takes tens of mA or more at a couple of volts. So a -5V supply and a resistor switched by a BJT works nicely for triacs, and +5 for SCRs and maybe acceptably for some triacs that are rated for Q4 operation (MT2 negative gate positive). But think of a low-cost phase-control ...

2

The characteristics of a passive network like this are very much dependent on the load impedance it sees. Obviously, the step-up scenario has half the load impedance of the step-down scenario, and this provides greater damping (lower "Q"). If your converter had feedback and dynamic control of the switching duty cycle, you could pretty much eliminate these ...

2

You are correct, their are two ways 3-Phase Meters can determine Import/Export Wh totals. I am a Electrical Engineer and have programmed EDMI smart power meters for customers in NZ who provide reconciled Import/Export kWh data to retailers for billing purposes. Option A is sometimes referred to as Net Metering and Option B, Gross Metering. Net metering is ...

2

Return current will be mostly in the shield of your coaxial cable, but that's not the problem. The problem is any changing magnetic field through that ground loop will induce a current that flows in the co-ax shield and that current will cause a voltage that looks like a signal to the receiver

1

Yes, that's the basic effect of the ESR (equivalent series resistance) and the capacitance of the cell. If you use any free circuit simulator and play around with reasonable values of R and C, you will get a better understanding of what's going on inside the cell. If you measure the given voltage drop with a known current and the time taken to recover, you ...

1

Why limit the alternator to producing 105A when the load requires more than that? So, allow the alternator to function with the "normal" regulation and it will cover the load as well as charging the battery. If the engine is under-sized and cannot produce sufficient power then the alternator won't be able to produce full output. Also, if the alternator is ...

1

N is the number of turns in a single coil of the motor windings. The maximum value of flux is the flux that the iron core for the coil can carry without being saturated. N and Phi are selected by the motor designer. Once the motor has been designed, everything that is of interest to the user of the motor is marked on a rating plate that is permanently ...

1

Insert a rise time and fall time for the pulsed voltage source. There are default values used when you input 0 that are realistic but >0, if you want to see more ideal behavior use a value like 1n. PULSE(0 5 10u 1n 1n 1.5434u 10u)

1

Triacs (and SCRs) only need a about 1.2V to trigger, so, yes, a 5V circuit could trigger one. Diacs have a kind of "snap action" when the threshold voltage is reached their voltage drop reduces to about 2V (allowing more curren to flow) until the current stops flowing. After breakover of the diac the current surge that flows into the triac gate is ...

1

I think this table is pretty accurate (even if technologies have improved) when considering the parameters (first column). Here the PowerMOSFET depicted is 500V/200A rated, which make them completely different to an RF "power" mosfet. When in doubt you can always go look online to electronic component resellers. Here is a common "High Power" MOSFET 100V/...

1

I'm appreciative of the solution by @Transistor which does work. I put this solution into practice and found that under no load the relay gets over 50 degrees C and emits a lot of EMI. I tried several relays to make sure it isn't a manufacturing defect. Darn. I replaced the relay with a DPDT switch instead. If this helps anyone else, it turns out that it ...

1

The view of an SCR, from what I read (and built, and tested) as a kid, is this simulate this circuit – Schematic created using CircuitLab Each side of the model provides voltage gain, and to "turn on" the SCR requires the GainSide1 * GainSide2 be > +1. The gain of either side is gm*Rload, where gm is the transconductance and Rload is 1Kohm for this ...

1

With the voltage source connect as shown in the schematic, the zener diodes are reverse biased and will (try to) clamp the input voltage to about the sum of their individual zener voltage. If for example D1 and D2 are a 4.7V zener and D3 a 6.2V zener, the clamp voltage will be about (4.7+4.7+6.2)V = 15.6V. If the input voltage is standard 15V, the zeners ...

1

Circuit breakers are mainly intended to prevent fires. They don't react quickly enough to block ESD pulses, and they don't react quickly enough to prevent many failure modes due to over-current in the protected equipment. What they do is prevent excess currents from flowing for minutes, hours, or days, which could overheat the protected wiring or equipment ...

1

There is a mechanism that kicks the circuit breaker into action, and it relies on current (not voltage) in the traditional circuit breaker. When the current reaches a certain level a coil triggers the spring loaded switch to turn off. Some breakers also have a bimetallic that triggers when it gets to hot in response to current. Source: https://electronics....

1

Multiplying $I_{RMS}$ by $V_{RMS}$ gives apparent power. This is the hypotenuse of the power triangle, where the other two sides are the real (average) power (in watts) and the complex power (in VARs). If, and only if, the load is purely resistive then the complex power is zero and the apparent power will equal the real power. In general, multiplying \\$...

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