Questions tagged [alternator]

Electrical generators that produce alternate current.

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1answer
42 views

Using bridge rectifier on failing alternator output?

I have a bridge rectifier (because it was what was readily available as an integrated part) rated at 150A which I'm using to protect against intermittent reverse current (battery draining) in an ...
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74 views

Car battery > inverter > battery Maintainer > Same car battery = jumper cables in the trash?

I'm wondering if I have my car battery hooked up to a power inverter hooked up to a battery maintainer hooked up to the same car battery will it prevent me from needing to jumper cable my car? I ...
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135 views

Designing an automotive alternator's voltage regulator - how to avoid magnetic saturation in the rotor?

Friends are making a test-bench for automotive ("Lundell") type alternators. They were supplied with an example alternator plus a voltage regulator module (the alternator requires external ...
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37 views

Three phase power supply for test purposes

I work in the electrical industry and deal with mainly three phase power. I'm trying to broaden my knowledge of scopes and power quality and the only time I really have to do this is at work and that ...
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1answer
89 views

Can steel nails be substituted for the silicon steel laminate in a motor/generator/alternator?

This is as diagram of a generator/alternator in which steel nails are used in place of silicon steel laminates:
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73 views

Honda CBX 1979 Regulator/Rectifier - Lipo (lifepo4) battery

I exchanged the OEM battery (PB) of the CBX 1000 motorcycle with a Lifepo4 12V battery. It is smaller, lighter and has a much better CCA. However, the connector (wires at the bottom side of photo) ...
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60 views

Charging battery using a three phase alternator

I want to charge a 672 VDC (182 kWh) battery pack using a 25 kW three phase alternator (679.8 VDC at 4000 rpm, current = 38.5 A). Can anyone suggest how to design the system? The alternator is powered ...
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3answers
107 views

Why are all the phases connected together on this old alternator

I got my hand on an old car alternator. I can't figure out how it works. What bugs me is that it look like all the phases (and neutral) are connected together right at the output of the stator coils. ...
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78 views

Shape of magnets used in an AC generator and its relation with the obtained waveform

Suppose we are dealing with an elementary AC generator having a single coil armature located between the curved north and south poles of a magnet(like the ones found in toy DC motors-only two poles). ...
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1answer
146 views

48V Lithium Battery Cutoff Detection Circuit

I'm building a power system using four x 48 V 100 Ah lithium batteries in parallel (48 V 400 Ah nominal). The batteries are already purchased, there is no going back. The cells cannot be accessed, ...
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86 views

What is the intuition behind the formula P = 2n in computing alternator stator poles?

So from my reference for alternators and even in the Internet, it says that the number of poles P, produced in the rotating field is P = 2n where n is the number of stator slots/pole/phase. I've seen ...
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23 views

Boost PFC with large leakage inductance

I would like to implement a boost PFC stage for an alternator that has a large leakage inductance (~40mH). When looking at the schematic, we can see that the boost inductance ...
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37 views

Wye-connected alternator changed from wye to delta

A wye-connected alternator is rated at 20 amperes of line current. The internal connections are changed from wye to delta. What is the new line current rating? From what I understood, to get the line ...
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1answer
77 views

How long should one let the motor turn (witout driving) to re-charge the car battery, after having using it to charge a laptop's battery [closed]

I'm going to spend 1 week with no electricity. I won't need any for everyday life (I do this each year), except to charge my laptop's battery (10.8V, 5.2Ah, 57 Wh) three or four times. I have a car ...
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770 views

How does a lead acid battery accept more current when it is discharged than when it is charged if the resistance is higher when it is discharged?

I'm just trying to get my head around the above question. It doesn't seem to follow Ohm's law. Could someone please explain what I am missing in this? Below is a chart I found of the changing ...
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314 views

How can I test the rotor winding of a single phase brushless alternator on a generator?

Context Generator runs but no power output from the alternator. The manual gives Ohm readings for the stator, excitation and rotor windings. The stator and excitation coil are to spec and have no ...
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118 views

Current limiting at 100 amps

What options exist for limiting current in this scenario? I have been searching for an option and it looks like I need to reduce the field on the alternator but I don't understand enough to know if ...
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32 views

Selecting Capacitor to reduce AC ripple from Car Alternator - LED Indicators only work when Engine Off

My neighbour has recently installed some aftermarket LED indicators, when the engine is switched off the units work as expected, switching from white headlight mode, to blinking yellow mode. When the ...
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2answers
103 views

Why does a change in excitation of an alternator affect only kVA and not kW?

http://www.brainkart.com/article/Effect-of-Change-of-Excitation_12208/ The explanation is there but I feel too dumb to be able to understand it and connect it to the visual. Can someone explain it in ...
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20 views

When changing rotor current in alternators, the pf and inductive part of the current changes but the resistive part does not. Why is this so?

Given a current for an alternator $ I = I_R - jI_X $ When the rotor current changes, the excitation changes so the magnitude of the generated voltage changes. The current changes, but only the ...
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102 views

Car alternator broken soldering joint

so it was very cold in my country last week and my car alternator died. I took it out and I found that one coil wire, which connects to rectifier is broken and there is no contact (I guess it could ...
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99 views

How is it that the induced EMF in an alternator is in quadrature with the main flux?

Looking at the simplified diagram of an alternator, the flux "linked" with the conductor is maximum at 90, 270 degrees, is also when induced EMF is maximum. So isn't the main flux in phase ...
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58 views

Counter torque in alternator supplying reactive power

When an alternator(assume zero armature resistance and iron loss) is supplying purely lagging/leading current, which means there is no work done by the current supplied, does that mean the counter ...
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2answers
62 views

How can you predict the power an electrical generator (alternator) produces?

We have to design an electrical alternator in a multiphysics software, but we can't seem to figure out how to deduce the power it will produce. We need to charge a capacitor to 1000 joules (at 2000V) ...
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96 views

Car Battery Voltage

Why is the voltage of a car battery rated for say 12V around 14V when the car is running? Is it because of the alternator?
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85 views

Regulating voltage from an alternator [closed]

I asked a question about voltage regulators but didn't get a proper answer, so here's a new one. So i have this motorcycle with an alternator. The alternator gives out about 3 volts at idle speed, but ...
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2answers
222 views

Determining number of poles on permanent magnet alternator

I was able to buy a cheap used permanent magnet alternator, however the seller was not able to tell me much about the specifications. I could determine that it has a built in voltage regulator, ...
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1answer
57 views

Which form between solar panel and wind turbines requires less cost in servicing?

I found that the average life of a solar panel is about 25 years and that of the the wind turbine is also somewhat close to 25 years. But the wind turbines require alternator in order to generate ...
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390 views

How can I calculate the internal resistance of an alternator?

I have a 12V, 90A alternator. I wanted to know how can I calculate its internal resistance. The specifications sheet I received from the manufacturer is a simple image, as shown below: I This ...
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141 views

Using rectifier + inverter to get 50Hz AC output

I am currently in the theoretical (until I am very sure that it is safe) situation that I have an alternator powered by a gasoline engine that provides 220V 1500W AC power with RPM dependent frequency....
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1answer
246 views

What determines the frequency of alternating current?

I am certain this question has been asked before but I search and cannot see anything just yet. I read most AC current is 60 cycles per second in the United States and some say 50 but that does not ...
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163 views

Old lead-acid battery inrush charging current

Can an old lead-acid battery have an usually high inrush charging current, such that the alternator belt squeals for the first 30-90 seconds after the engine is started? It is worse in hot weather. ...
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2answers
74 views

Is the calculation of weight to be suspended inorder to produce electricity from an alternator correct or not?

I bought a alternator with the following specs: power: 5 hp rpm: 1800 voltage: 220V The formula for finding the horsepower is: horsepower= (RPM X Torque)/5252 By substituting the value of horsepower ...
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384 views

Alternator output rating

Overview: I am currently working on a project that requires a 24v alternator, which is powered by a mower engine. This engine in particular runs around 3,000 RPM, and does not exceed 3,200 RPM (based ...
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2answers
2k views

Tantalum Capacitor Explodes When Engine Starts

I designed a circuit using a SMPS voltage regulator based on the tps65261rhbr triple synchronous buck converter. The circuit is rated for up to 18V. It is connected to a 12V lawnmower battery, which ...
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69 views

An AC generator can 'lock up' if its timing is off? [closed]

I believe I read elsewhere on Stack Exchange (Physics or Electrical Engineering) about how an alternating current generator can seize up if the frequency of the current does not match something else ...
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1answer
102 views

Modifying brushless alternator for external regulator

I'd like to modify a Delco Remy 38si or 40si brushless alternator for use with an external voltage regulator. For a brushed alternator, I'd just need to pull the field out external to the case. My ...
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1answer
45 views

Selecting the right PMDC motor and battery

I'm looking at generating electrical energy from a mechanical input being used to rotate the shaft of a Permanent magnet DC motor. However, i'm a bit stuck with selecting the right motor and battery ...
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1answer
319 views

Attempt to build DIY high current power supply from car alternator?

Recently I had posted about a thread related to a bench DIY high current transformer 12VDC supply that I'm trying to built. But due to some transformer and diode rectifier limitations that project may ...
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3answers
1k views

How can excitation be used of an alternator to control the power factor?

Looking for ways the excitation of an alternator can control its power factor?
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161 views

How to wire a single wire alternator to a bridge rectifier?

I'm trying to make a 25cc weed eater generator (for fun) and I'm thinking of using an alternator to take the rotary output from the engine and turn it into electricity. I need a way to take the 12-14V ...
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2answers
394 views

To what extent are alternators "flexible" to variations in input speed and output voltage?

An automotive-style alternator works from 750 RPM to e.g. 7000 RPM, a range of nearly 10:1. In terms of output voltage, I know they target a fixed output voltage, but I believe it wouldn't be too ...
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49 views

Finding Impedances on a Network

Hey there the first part of the question (finding the new C value) is pretty easy. However I am stuck at the second part, it asks me to find the empadance values and etc. Can you help me with that?
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369 views

What will happen if the prime mover driving synchronous machine is accidentally disconnected?

What happens to a synchronous machine connected to an infinite grid, acting as a generator, when its prime mover fails i.e. when mechanical input at the shaft reduces to 0? I'm assuming that the ...
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66 views

Improving a permanent magnet alternator. Replacing magnets / reducing air gap

In the case of a 3 phase PMA radial flux type, used as a wind turbine, with magnets on the surface of the rotor, is it safe or even doable to stack another magnet with the same geometry on top of the ...
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87 views

Relating input torque on BLDC motor shaft with output current

I am trying to build a drone generator with a gasoline engine and a 14-pole,170KV, 2KW BLDC skateboard motor (this one). Before designing the system and running it, I wanted to clear out a fundamental ...
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138 views

Current delivered by the vehicle alternator

I have a vehicle alternator with following parameters: 14V, 140A. In parallel to this alternator is connected 14.4V vehicle lead acid battery. The alternator is used as a power source for a load which ...
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86 views

Control of battery charging

I have been developing a control software for charging and discharging battery in a dc grid. The system consists of: 01) Three phase alternator with three phase diode bridge rectifier at its output ...
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559 views

Excitation current calculation for alternator

I have an old brush alternator where field excitation happens in the stator. Unfortunately no information is given about the required field excitation current. The alternator is rated 3 Phase, 400V, ...
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1answer
45 views

Selecting an alternator/generator

I am designing anenergy regeneration system using a pulley attached to the wire rope of a track elevator using a 3:1 sprocket ratio I am getting around 670 RPM`s I am using two 6 volt lead acid ...