ARRAY electronic loads

[Alex]

Hi, I was just wondering if anyone has had any experience with the Chinese ARRAY (rebranded?) electronic loads:
http://www.array.sh/yq-3700e.htm

Any info would be useful!

[Short Circuit]

Readings are not very accurate, and PC control next to worthless, clumsy terminals.
But overall, it's very good value for money. Offers various load modes, such as constant current, constant power, resistive.

[olsenn]

I stand by the performance of my Itech (BK Precision) IT8511 DC electronic load... it is wonderfully designed and worth every penny if your work requires such a device

[bsgd]

I am also looking for a electronic load for my lab, but I dont wanna spend a fortune... if you guys have some nice and cheap recommendations it would be pretty nice!

[olsenn]

In my opinion, NEVER CHEAP OUT! If you only need a power resistor for something in particular than that will be cheaper and more reliable than any electronic load, but if you are going to go for a professional tool like that, then you're better off paying $500 for something that will last forever, as opposed to something that either breaks down in a year, or is so pathetic in terms of features and accuracy that you'll end up buying that $500 one eventually anyways, the $150 one will end up in a closet (and never come out again) and you'll have spent $650 for something that you could have gotten for $500.

That being said, if you are hell bent on spending no more than $200, then have a look on ebay; they have an assortment of cheap DC loads.

[Alex]

Thanks for the replies.
Pretty much what I would expect Short Circuit, at ~£200 it is excellent value for money as you say. Have you pushed it to the higher end of its power dissipation capability? Does it feel like it will blow up?

Olsenn, could you comment on the PC communications for the IT8511? It would be very useful to setup a test waveform on the PC, download it to the load and have a scope syncronized to the output of the PSU under test.

Unfortunately high(er) voltage PSUs will frequently be tested, 140, 250V DC come to mind at a low current 1-10mA. The ARRAY 3710A quotes 2%+3mA accuracy in this range, so I will probably need a DMM too for current measurement if I am to have any confidence in it. From the Itech line the IT5812B can go up to 500V and the current accuracy quoted is 0.1mA (no further info is given on that figure).

The (looking on ebay) BEICH CH8710B looks like it is the same hardware as the ARRAY device, with a different screen. It can do up to 360V. There is also the M9712B that goes to 500V and seems similar to the Itech/BK unit, VFD screen etc. I cant make out what brand it is, here have a look if you can figure it out. It starts with an 'M'. http://cgi.ebay.co.uk/ws/eBayISAPI.dll?VISuperSize&item=130600015278 This goes for £477.

EDIT: Olsenn I am of the same philosophy too, but its not always black and white; budget is always a factor. Agilent and Kikusui also make electronic loads. No need to splash out when you can get the quality and specs you want a bit cheaper.

Lets see how much we can get the IT8512B for.

[olsenn]

It would be very useful to setup a test waveform on the PC, download it to the load and have a scope syncronized to the output of the PSU under test.

hmm, I'm not sure you understand the principle of a "DC" load: you don't download a waveform to an electronic load, that would be an arbitrary function generator, and I don't see the need for an oscilloscope???

The software for the IT8511 (and all 8500 series loads) is in my opinion, excellent. In addition to the software provided from BK Precision (that's right, they make and support the Itech line) LabView drivers are also available for download. The only concearn you may have is that it costs an additional $50 from Mouser to buy the TTL-to-USB (or TTL-to-RS232) cable that is required to connect it to a computer. One plus to this cable is that it is optically isolated.

The device itself is built like a brick shithouse, very robust and fully featured. It surprised me to see that the LCD readings (and those reported to the computer) are largely accurate to three decimal places (tested with my Fluke 87-V and Rigol DM3058). I've also tested it to it's full rated power capacity of 150 watts and more (it actually will allow you to run up to 200 watts or something around there). Full over-voltage, over-current, over-temperature and reverse polarity protection is in place.

[Alex]

hmm, I'm not sure you understand the principle of a "DC" load: you don't download a waveform to an electronic load, that would be an arbitrary function generator, and I don't see the need for an oscilloscope???

I take it in the software you can set a few 'DC' operating points (say 100R, 50R, 10R) in time and have the load run those in sequence, right? The scope for various key nodes on the unit under test for transient response.

Sounds like a worthy unit, or you are a good salesman, or both.  Fired off a question to Caltest. Place your bets!

[olsenn]

I take it in the software you can set a few 'DC' operating points (say 100R, 50R, 10R) in time and have the load run those in sequence, right? The scope for various key nodes on the unit under test for transient response.

Oh, I see what you mean -- yes, you can do that. If you need to know the switch times I'd recommend you look at the datasheet first though.

Thanks for the compliment, haha, I'm sure you'll like it.

[Alex]

Thanks BaW for that brand. Why did your reply ('Maynuo.') got deleted?

Here is the Maynuo M9712B, similar specs to the IT8512B with some notable differences at shortcircuit resistance and pulse tests.

http://www.maynuo.com/english/xpro.asp?pid=53    (warning, very slow page download)

I tried downloading the software but at 1.3kB/sec it was not practical.

If you look at the page linked above, they have a screen cap. Does that look familiar olsenn? 

[nctnico]

I recently bought two Array 3710A loads (the 150W model). They work ok for testing power supplies. Fortunately the fans only switch on when they have to. The only downside is that they use relais to switch between the two load cells inside. Depending on the load / voltage they change over which causes interruptions on the load presented on the input. I converted one the have 4mm style inputs. The build quality is OK. Actually the casing is an exact copy of old style HP equipment 

[NiHaoMike]

Maybe use incandescent light bulbs or heaters with PWM control? The hardest part of building a large load is dissipating all the power, which is what the heaters or light bulbs do very well. A grid tie inverter can recycle a large percent of the power, but it only makes sense if you're doing a lot (as in near 24/7 burn in tests at a factory) of high power testing.

[bsgd]

I have 2 BK 8500 loads and I like them a lot. At first I was inclined to get an Agilent 6060B, but it was kind of expensive and getting two would cost me too much.

[nctnico]

Here is a picture of the inside of my 3710. Note that I modified the input connectors!

[Rufus]

Inside of a Beich CH8710B.

Cheap and Chinese same as the rest. I am pretty disgusted with all these loads. I haven't seen one specify a maximum voltage rating between inputs and earth. I assume they all have all the internal circuity tied to the -ve input and floating with respect to earth.

Cracks me up, the BK and Itech manuals have a page full of safety drivel but neglect to tell you that if you stick 360v on the +ve input terminal you are going to get 360v on the pins of the 9 way 'D' comms connector on the back.

This Beich has RS232 conversion built in but it isn't isolated, at least the Itech etc want you to buy a comms adapter which if you believe the label on it is isolated but nothing tells you why it needs to be.

[EEVblog]

Hi, I was just wondering if anyone has had any experience with the Chinese ARRAY (rebranded?) electronic loads:
http://www.array.sh/yq-3700e.htm

I was wondering about those, they go very cheaply on ebay.

Dave.

[codeboy2k]

Here is a picture of the inside of my 3710. Note that I modified the input connectors!

in that picture on the left hand side, note the curvy traces on the PCB. Can anyone tell me what's the design decision
that went into making those traces like that.  Obviously the shortest path is a straight line there, and it's clear
where a straight line would go.  But they didn't go straight, and I can't imagine there is anything high-speed here, so
it's not a strip-line or matched impedance like that.   I've also seen it done this way on the battery connections inside
cell phones  and home phones.  In those cases, it's almost like an RF choke on the PCB, but I can't see why such an RF choke is needed here on the DC load.  Anyone know why's it done that way here.

[nctnico]

The designer probably wanted to add some extra resistance. The traces go to 2 low value wirewound resistors in series.

[EEVblog]

I have 2 BK 8500 loads and I like them a lot.

Looks like I might be getting a BK Precision 8500 load shortly, so stay tuned...

Dave.

[Rufus]

Beich CH8710B issue and fix.

One problem I noticed with this load was significantly low voltage readings at higher currents. The photo shows the back of the input terminals and L shaped bars which are bolted on the back of them and soldered to the analog PCB.

The input voltage is sensed on the PCB and I measured about 15m ohm between one terminal and the PCB and 40-50m ohm on the other. The terminals have M6 studs and the bars were fastened with a flat washer, single turn spring washer and M6 nut (which was tight).

The resistance appeared to be between the terminal studs and bar so I replaced the flat and spring washers with slightly domed spring washers with a serrated surface (think they came from earthing screws supplied with a large diecast box). With that fix the resistance between terminals and PCB was about 0.5m ohm both sides.

Shows bolting together two bits of metal doesn't necessarily make a good electrical connection.

The washers I used were something like here http://www.bellevillesprings.com/serrated-safety-washers.html

[codeboy2k]

I have 2 BK 8500 loads and I like them a lot.

Looks like I might be getting a BK Precision 8500 load shortly, so stay tuned...

Dave.

...waiting for its Tuesday...

[bsgd]

I have 2 BK 8500 loads and I like them a lot.

Looks like I might be getting a BK Precision 8500 load shortly, so stay tuned...

Dave.

Great Dave, a teardown/review would be awesome!

[EEVblog]

Great Dave, a teardown/review would be awesome!

That's the idea.
Will be handy for the PSU and other stuff too.

Dave.

[saturation]

An interesting application of the Array 3710 and 3711:

http://www.techpowerup.com/articles/overclocking/psu/161

[T4P]

That was my gripe with 95% of the Tech websites PC PSU reviews, largely inaccurate measurements