# Questions tagged [power]

Where power is a primary concern for the design under discussion. Use the "low-power" tag when that applies.

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### How to supply power to a DC motor which will be used for an electric skateboard?

I bought a 775 DC motor 15000RPM 12-36V. I'm planing to build an electric skateboard with it. But I don't know how to supply enough power to this motor in order for it to carry me with a decent speed. ...
64 views

Looking at an ENTSOE paper, I have seen this table in which the typical ''loading factors'' of different generation types are listed (see figure below). But, what is this???? I was supposing that it ...
18 views

### What is the rating of a transformer which connect a generator to the MVgrid?

What is a typical power rating (MVA) of a transformer which connects a synchronous generator to the MV grid? I would think that there is just a safety margin compared to the rating of a generator, for ...
1 vote
139 views

### How to reduce power drawn by a resistor heater?

I am rather new in this field. On 220V AC industrial power supply, a 6 ohm resistor heater (nichrome wire, 0.40 ohm/m, 15 m) will draw about 8067 watt of power. About 2400 W are needed. What are the ...
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37 views

### Transformer ratio of a transformer that connects a generator to a MV grid?

Inside my one-line diagram in which I am studying some properties of the medium voltage grid, I want to connect a generator to the MV busbar to study the hosting capacity. Therefore there is not a ...
45 views

### How can I step down 24V to 5.5V and 3.3V with separate grounds?

I have a 24VDC 4A input that I need to step down to both 5VDC and 3.3VDC, but I need the 24V ground plane to be separate (isolated) from the 5V and 3.3V plane (these can have a shared ground). What ...
17 views

### How do you combine state space models of a large power circuit having control circuit?

I am trying to model a hybrid network using state-space representation. How do I start? I have modeled the individual circuit figures. but I don't know how to proceed with combining the control and ...
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### Driving multiple strips of LEDs

This might be a very basic question but I am just starting out on my electrical engineering journey, and would like to check something. I have a simple LED design running at 12V, currently I have 12 ...
1 vote
32 views

### Conceptual understanding of phase power vs. line power

I am looking at two formulas: P = √3 x VL x IL x Cos Ф P = 3 x VPh x IPh x Cos Ф Now assuming P here refers here to the total power. Could I take VPh and IPh and combine those terms as P (Phase)? Same ...
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1 vote
77 views

### How to calculate the total power of a LED using solid angle?

I have a LED with the max power of 130mW/sr and an opening angle of +-10° (so approx. around 20°). I conducted an experiment using this LED, the LED shines light to an un-doped silicon semiconductor ...
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46 views

### Output reflection coefficient of a power amplifier

I'm struggling to understand the implication of a poor large signal reflection coefficient at the output of a power amplifier. I designed a power amplifier and checked the large signal S22 (for the ...
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1 vote
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### How to regulate 5V 3A to 3.3V for ESP32 and level up 3.3V to 5V on a PCB?

I'm making my first custom PCB with an ESP32-WROOM-32E. I am following this tutorial for the ESP32 part. My project requires a 5V 3A power supply but the ESP32 only takes 3.3V. The tutorial uses an ...
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### Voltage is below 380

I am Vango from Ethiopia. Am junior electrical engineer. While working today I've faced some problem. That is when incoming voltage drops below 380 V, I mean when it is about 370 V, motor stops ...
89 views

### How can I make this variable power supply go from 1.25V and -1.25V to 0?

I'm trying to learn and in this case I have a power supply circuit that has a fixed 5V, a 1.25 to 12V and a -12V to -1.25. I understand that the regulators I'm using have a minimum limit output of 1....
17 views

### Power factor of a synchronous based DER

I am working on a project including a synchronous based DER (2 Gens).I have a few question, I'll appreciate if you could help me. 1- I want to see what would be the typical control-mode setting of the ...
112 views

### Power supply overload protection work around

I have the following power supply here I need to switch on a contactor that uses around 3.2A inrush current for around 20ms (I cannot find the datasheet for this). Now the power supply breaks down the ...
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### Connecting LiFePo4 in series?

I am looking for 3 LifePo4 batteries for a project, since they are quite stable when compared to Li-po/Li-ion. I have found this battery that fulfils the max amp draw requirements. I need three in ...
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### Why do I get this output voltage? Push-Pull converter

I am expecting a push-pull converter behavior from this circuit, but I can't figure out what I am doing wrong here. I am using the free version of SIMetrix/SIMPLIS The output looks like this, a flat ...
2k views

### How can a reed switch be used for high current applications?

I am planning to use a reed switch as a power switch in my underwater robotics project. The switch will be placed between the LiPo battery (16.8V, 20.8Ah) and the load. The load mainly consists of two ...
45 views

### Is there a dedicated device for this scenario? [closed]

I'm looking for a logic device or a relay etc. which detects the DC current when it is above a threshold. Basically my system is as follows: I want an LED to turn on when the device sinks more than ...
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### dB (decibel) is a relative measure. It's not a physical unit. Decibel relative to what? [closed]

dB (decibel) is a relative measure. It's not a physical unit. Decibel relative to what? The answer is: Relative to power
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### What causes voltage drop when powering both 8-relay module and DE-10 Nano simultaneously using 5V and 0.84 Amps through a power supply?

I have a robot that have uses DE-10 nano fpga board stacked on top of another pcb board that acts as power distributor to other components such as linear actuator brakes, wheel brakes, spray gun, etc ...
26 views

### Apparent power for assymetric configurations

I know that the total apparent power S in a 3 phase load for Wye-Wye or D-D configuration = sqrt(3)Vline*Iline. Is it the same for Wye-D or D-Wye configuration?
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### Measure power with multiple measurements

I want to measure the mean power draw of a Jetson Nano. I did this by using a digital multimeter and running the measurement 60 times with a fixed integration time of 0.3s. The result of each ...
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### How do you add multiple system voltages to a design? [closed]

I have been trying to search and been hitting a roadblock. My system uses a 42V Li-Ion Battery in an E cycle. The controller I am designing uses the following voltages 3.3V/100mA for Logic and ...
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### Could someone please tell me what each of these components are?

I'm hoping someone could please identify the components in the picture below. The input is 32A, 3P from a variable frequency drive. The bottom most symbol has been identified as pumps/fans/HVAC/etc, I'...
78 views

Let's consider the case of linear dipole antenna or Hertz dipole. I know that the antenna acts as a transducer and it radiates the E-M waves due to the acceleration and decelaration of the electrons ...
1 vote
101 views

### Can a CPU heatsink be used to cool a TO-3P or a TO-220?

I want to know if my thermal design is appropriate for dissipating 72W of heat while keeping the junction temperature below 150 °C (I am trying to cool an SFH154 that comes in a TO-3P package). My ...
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### Determining the characteristics of an unidentifiable low-frequency transformer

I am in possession of a collection of salvaged transformers. I am curious about this one in particular: I gather from its laminated core that it is intended for use at line frequency. What I assume ...
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### LDO units for noise [duplicate]

In this Link, on page 6,they have mentioned the LDO noise in terms of uV/(sqrt)Hz. Can someone tell me what does this unit mean and how to understand this unit?
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### Power injection LED strip: best method art instalation?

I'm building a modular art installation consisting of multiple 1 meter LED bars. From the power supply / microcontroller there are multiple lines consisting of 2 - 6 bars. The led strips I got need ...
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### Addressable LEDs (WS2815): power and data in a multicore cable

Would it be possible to use a multi-core cable to have power and data in the same wire? I'm using WS2815 LEDs. The total current needed is 9.6A. For a cable of 8 meters, a 2.5mm wire is needed. ...
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81 views

### Battery capacity and parallel vs. series battery connections

Say you have 4 200 Ah 12 V batteries connected in parallel, this as I’ve come to learn increases the amp-hour value and not the voltage, and say you have another system same as that but connected is ...
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1 vote
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### Relation between line voltage and phase voltage in delta configuration

I have read answers pertaining to this same question, but I could not understanf why the phase voltage is equal to line voltage. This answer says: In a delta system, the two points required to ...
72 views

### What is the real and apparent power of these steel cutters?

The US market model of this steel cutter is 120 VAC, 13.0 Amp. The NZ market model is 230 VAC, 1,100 W. I am trying to wrap my head around whether 1,100 W is the real power and so whether the apparent ...
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### What is the suitable battery to power 5 servos?

I have 5 servo motor types of Futaba s3003, I want to run them simultaneously so I'm asking what is the right battery should i use? according to the datasheet: https://www.es.co.th/schemetic/pdf/et-...
56 views

### Soft Latch ON-OFF with support of DC High Voltage side, compatibile with Arduino or any Low Voltage MCU (with schematic)

First Schematic I'm trying to implement this schematic that I found in this interesting article (Soft Latching Power Circuits). This is a circuit can substitute a mechanical on off switch, and use ...
22 views

### Electric Motor unbalanced voltages

Why unbalanced currents are 6 to 10 times voltages unbalanced? Source: Energy management handbook by Steve Doty and Wayne C. Turner Eighth edition ISBN 0-88173-707-0 Published by The Fairmont Press, ...
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### Kiln SSR zero-cross frequency

I am planning on using a WATLOW DC2T-24C0-0000 power controller for a three phase electric kiln. It is a zero-cross 3 phase, 2 leg controlled contactor capable of driving 46 amps with its huge heat ...
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### What exactly is power? And what limits its generation?

I know that P=I*V, and that when power is constant then current is inversely proportional to voltage. In case of transformers, stepping down voltage increases current. I was told that this because of ...
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1 vote
44 views

### Fault impedance type?

Usually fault impedances are resistive type. But is it possible to have a mix of resistive and reactive component in fault impedances? Looking at many simulation tools, they give the possibility to ...
1 vote
33 views

### PSRR of an amp + ADC input stage

I have an input stage that consists of an amplifier then an ADC. The op-amp and ADC are powered by Buck voltage regulators. I want to measure the PSRR of this stage, so I am planning on breaking the ...
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### Is it true reactive power loads cause more voltage drop than do similar-size (MVA) real power loads

Per the site below: https://electrical-engineering-portal.com/how-reactive-power-is-helpful-to-maintain-a-system-healthy#Importance%20of%20Present%20of%20Reactive%20Power ** Is it true reactive power ...
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### How to reverse voltage 12-24VDC to use a peltier element for heating and cooling

I'd like to use a standard peltier element as a heater and a cooler. The specs should be something around 12VDC, 30W. Electromechanical relays are not an option, the peltier should be used to regulate ...
53 views

### Powering esp32 via v5 influences ds18b20 working (which is powered with 3.3v)

I'm running a wire of 12 ds18b20 sensors on a esp32. The wire (utp5 cable) is 1m to the first sensor, and then 15cm between every sesnor. Power via 3.3v pin of the esp32 (wroom32 dev board) a resister ...
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1 vote
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### How can I select a suitable cable with these characteristics: 690 V, 550 A, 1 km long, AC three phase underwater cable

How can I select a suitable cable with this characteristics: The cable is connected at one end to a 690 V power generator that is between 6 and 40 meter below the surface of a big river and converts ...
58 views

### Charging Power Banks from Electric Car Charging Stations (DIY, LiFePO₄)

Is it possible to charge my own Lithium-Ion Battery Bank from pay-to-use Electric Car charge stations? I’m traveling in an (ICE-powered) caravan. I have a 0.7 kWh Lithium-Ion Battery Bank and a 100 W ...
45 views

### When I connect a battery, the system fails

I have a standalone PV system with boost converter using perturb and observe (P&O) as the MPP algorithm. The values of input, output capacitors, inductor are calculated correctly based upon a ...
1 vote