Looking for a 20A, 500W AC power supply - Page 1
Forum section: electronics / testgear

author: j_omega
author_rank: Contributor
timestamp: July 14, 2022, 04:29:10 pm
content: I am looking for an ~500W AC power supply that can deliver 20A rms and runs off of 120V wall power. I have looked through all of the major vendors (BK Precision, Preen, Instek) and haven't found anything that meets those specs. The only supplies that I can find are >2000W supplies that run off of 220V. Does anyone have a recommendation?Edit:I also want to be able to adjust the output voltage (0-25V rms) and frequency (100-1000 Hz).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 14, 2022, 04:40:43 pm
content: https://www.alliedelec.com/product/solahd/e500e/70209185/meets exactly all of your specifications.Tim

author: Martin72
author_rank: Super Contributor
timestamp: July 14, 2022, 05:12:30 pm
content: QuoteHmmm....More details ?

author: j_omega
author_rank: Contributor
timestamp: July 14, 2022, 05:26:29 pm
content: Quote from: j_omega on July 14, 2022, 05:26:29 pmSimulating the output of a permanent magnet alternator. At full power, the alternator delivers 12 A rms at 14V rms. I currently have a mechanical test bench that I would like to replace.

author: j_omega
author_rank: Contributor
timestamp: July 14, 2022, 05:29:16 pm
content: Quote from: T3sl4co1l on July 14, 2022, 04:40:43 pmI guess I forgot to specify that I wanted to be able to adjust the output voltage (0-25 V rms) and frequency (100-1000 Hz). A variac would almost be sufficient, but I would be stuck at 60Hz.

author: Kean
author_rank: Unknown
timestamp: July 14, 2022, 07:40:17 pm
content: The problem is that most adjustable AC power sources will be designed for a wider voltage range than you require - e.g. voltage ranges of 150V or 300V.The ITECH IT-M7723E can output 15A RMS in the 100V range (1500VA max) and according to the manual it can run from 110V AC input. It is quite possibly overkill in terms of features and price for your needs.Websitehttps://www.itech.sh/en/product/ac-power-supply/IT-M7700.htmlThe user manual is available for download athttps://www.altoo.dk/ITECH+IT-M7723E+1500+VA+Programmable+AC-DC+Power+Supply.htmThe IT-M7724 can output 30A RMS, but as it is rated for 3000VA total it may not be designed for 110V operation. Plus it is huge and likely expensive.

author: j_omega
author_rank: Contributor
timestamp: July 14, 2022, 07:55:39 pm
content: Quote from: Kean on July 14, 2022, 07:40:17 pmThanks, that looks like it might do the job. I submitted a quote request. Alibaba says they cost about 3,600 USD new.https://www.alibaba.com/product-detail/ITECH-IT-M7723E-300V-15A-1500VA_1600051479714.html

author: Kean
author_rank: Unknown
timestamp: July 14, 2022, 08:01:56 pm
content: As you are in the USA, you could also tryhttps://www.circuitspecialists.com/ITECH-Electronics-Test-Equipmenthttps://www.itechate.com/en/product/ac-power-supply/IT-M7700.html

author: Hexley
author_rank: Regular Contributor
timestamp: July 14, 2022, 09:25:25 pm
content: Quote from: j_omega on July 14, 2022, 04:29:10 pm25 volts and 20 amps implies a 1.25 ohm load; and 100 to 1000Hz is comfortably within the audio range. So maybe you can look at a "mono block" audio power amplifier, and surround it with the rest of the bits needed to flesh out your requirements.For example, you could integrate the following:A cheap function generator to generate sine waves of adjustable frequency. That drives:An audio power amplifier rated to deliver 20 A into a 1.25 ohm load. Might be able to use a cheapo Class D amplifier intended for car audio.A 12V/50 amp switching power supply to run the power amplifier.True, this makes for a multi-box solution. But if you are putting together a specialized test bench, maybe that could be managed?

author: Martin72
author_rank: Super Contributor
timestamp: July 14, 2022, 10:39:01 pm
content: Another relative cheap solution could be a VFD = VariousFrequencyDriver.They are used to control motors, pumps...They are also avaible for 120Vac input single phase.Problem:They´re tons of different types on the market avaible...Important would be a single phase output, an adjustable output voltage which fits the needs (25Vrms), output frequency up to 1000hz.Single output and frequency wouldn´t be the problem, I saw VFDs even up to 5000Hz.Problem oculd be the output voltage.You have to look for a one, who is completely free adjustable.But i got a feeling, there is one in the www....Just an Example

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 14, 2022, 10:46:44 pm
content: Ah, that makes more sense then.Agreed, get an audio amp of suitable rating, calibrate its gain, use an isolation transformer (on the output) if necessary (easy enough to use a 12+12V or 24+24V 1kVA toroid and leave the primaries unconnected, just use the two secondaries -- which reduces capacity, hence 1kVA).Don't forget an inductor (possibly a tapped one, with whatever switching/adjustment you find necessary and suitable) to get the output impedance correct. On the order of (12V / 12A) / (2 pi (100Hz)) or 1.1 to 11mH.Tim

author: j_omega
author_rank: Contributor
timestamp: July 15, 2022, 03:24:33 am
content: Quote from: Hexley on July 14, 2022, 09:25:25 pmQuote from: T3sl4co1l on July 14, 2022, 10:46:44 pmI actually already looked into the audio amplifier idea. I planned out a system using aRockford Fosgate R2-750x1amplifier powered by aMeanWell SE-1000-12supply. Initally, this appeared to be a very affordable solution. However, as I was double-checking all of the specs, I noticed that the frequency response of the amplifier was 20-250 Hz. After looking at several other amps, I realized that this was normal. Some go up to 500Hz but that seems to be the limit. I believe this is because they are intended to drive large bass speakers.I also haven't spent much time in the audio world so I may be looking at the wrong things. Can you point me in a better direction?

author: j_omega
author_rank: Contributor
timestamp: July 15, 2022, 03:25:22 am
content: Quote from: joeqsmith on July 15, 2022, 01:20:20 amThe battery is unrelated to this project.

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 15, 2022, 05:43:28 am
content: You need a hifi/PA amp, not an automotive subwoofer amp, should be pretty flat from 20Hz-20kHz. Or build one, they aren't terribly complicated.

author: j_omega
author_rank: Contributor
timestamp: July 15, 2022, 03:33:09 pm
content: Quote from: BrokenYugo on July 15, 2022, 05:43:28 amThanks, that helps a bunch. You're thinking of something like this, correct?https://www.crutchfield.com/p_859XLS1002/Crown-XLS-1002.html?tp=63633

author: j_omega
author_rank: Contributor
timestamp: July 15, 2022, 03:43:18 pm
content: As far as I can tell, something like this should work?https://www.ebay.com/itm/165019291586It uses theTPA3255amp for TI

author: aagw
author_rank: Newbie
timestamp: July 15, 2022, 04:52:08 pm
content: I have used EP4000 from Behringer with great success when testing some track circuit relays, which must have 95/105Hz.https://www.behringer.com/product.html?modelCode=P0A37Lots of power

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2022, 09:31:06 pm
content: What the "Audio Solution" concerns, we (at work) got three of them.One is a testsetup for resonance circuits, checking and adjusting coils.Got a Sinewavegenerator, a 1400W PA-Amplifier and a Pre-Resistor on the output to make sure, the amp won´t be damaged if the coil is getting saturated.Second is a setup for checking inverters, same as before but with transformer for galvanic isolation on the output and no pre-resistor.The third is somekind of special...It uses three "High-End" PA-Amplifiers with 2.5KW each, driven by a 3-Phase sine with free adjustable frequency, delivers up to 135Vrms/phase on 4 Khz...I have some doubts about using a really cheap Class D amp for this purposes, but I can´t put it in the right words actually.Must think about it.

author: j_omega
author_rank: Contributor
timestamp: July 15, 2022, 09:36:53 pm
content: Quote from: Martin72 on July 15, 2022, 09:31:06 pmI did some more looking at the pro-audio market and found some nice offerings from Crown, QSC, Yamaha, and Behringer. For this purpose, does the class of amplifier matter (AB vs D)? I can find some name-brand high-power AB amps on eBay for great prices.

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2022, 09:46:11 pm
content: For the third solution, we got the amplifiers from crown, because we must make sure the power will be constantly avaible.In this case it must be top quality.We use this setup for tests who last more than three days nonstop under full power...For the other we use indeed "cheap" Class AB Power Amplifiers from "Monacor" or newer IMG stageline.

author: aagw
author_rank: Newbie
timestamp: July 16, 2022, 12:46:15 am
content: Quote from: j_omega on July 15, 2022, 09:36:53 pmIf you choose a class-D amplifier, you will most likely have some switching ripple on your output signal.It could be annoying when measuring with a scope for instance.

author: MikeP
author_rank: Regular Contributor
timestamp: July 17, 2022, 09:31:00 am
content: Quote from: Martin72 on July 15, 2022, 09:31:06 pmWhat is the signal source for amplifiers?I'm mostly interested in a three-phase PWM generator. I will be grateful for any help.

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2022, 10:51:40 am
content: Hi,Source is a selfbuild three phase generator and "of course" I can´t tell anything about it.But you can try to get a cheap VFD and do some reverse engineering on it, most VFD got three phase outputs...