Tekpower TP3710A Programmable DC Electronic Load, 150 Watts, Low Ripple

This is a review of the 150W, TP3710A Programmable Electronic Load____________________________________________________________TL;DRThis is a good unit. Solid, reasonably user-friendly, quiet when idle, and meets its specs. The software that comes with it is old-fashioned but serviceable (I run it on Windows 7). It comes with an adapter through which you can connect it to a PC through the included USB cable. If you want to program it yourself it speaks SCPI (a standard instrument-control language).It also comes with a test report showing 22 measurements that they made and the numerical results of each to verify its performance.____________________________________________________________PERFORMANCEI ran this for two days at 180 Watts -- one day 30V at 6A, one day 60V at 3A. It ran without a hiccup. all the fans when running at full blast were loud but not so much that I couldn't do computer work about three feet away from it.It seems to do a good job of reporting the actual current, voltage and power at which it is operating.Setting desired load current or power seems to be reliable and accurate.I've experimented with setting the load resistance but have not yet fully characterized its behavior.I have not yet tried any of the more advanced functions.Unlike for some of the reviewers my knob works perfectly: each click changes the setting by one unit.____________________________________________________________SOFTWAREThe "E3710A" program looks like it was written in about 2003. The visual design is very old fashioned, it's somewhat disorganized and awkward, but ultimately does the job. You can control all the functions of the unit, create and run a 10-step "program" of different load levels, and datalog the operating current, voltage, power and resistance at selected intervals.The "Discharge" program, apparently for datalogging the characteristics of a battery as its discharged, runs but I haven't tried to use it yet.____________________________________________________________GENEALOGYThis unit is manufactured by Array in Taiwan and sold under various brand names, including: Tekpower, Circuit Specialists and Gossen Metrawatt.Tekpower appears to be a brand name of Kaito USA, whose Amazon.com storefront is named Electronnix.____________________________________________________________SUPPORTI called Kaito USA to get tech support on the included software. They answered quickly, routed me to a tech, who routed me further to another person, who fired up a unit and ran the software. It didn't sound like either of them were experts at this product but I ultimately got the information I needed to understand why the "Excel" button on the software wasn't working for me.There was no warranty card included with the unit, but tech support said that they warranted it for one year.____________________________________________________________IDIOSYNCRASIESo Although the case looks perfect and is quite solid, it is slightly twisted. If I place it upright on a flat surface and rock it back until three feet are solid, the fourth foot is about one millimeter in the air. If I place it upside down on a flat surface it's similarly warped. I've never had a piece of equipment do this, but it looks and works perfectly so I'm not going to worry about it.o Unlike most datalogging software I use, the "Excel" button doesn't simply save an Excel-compatible file; rather it launches Excel, creates a new spreadsheet and fills it with data. If you don't have excel installed (like I didn't at first) pressing the Excel button pops up the error message "class not registered".o It looks like only the USB cable that comes with the unit will work. A longer, USB 3 compatible cable didn't work. A USB 2 extension cable added to the included one didn't work.

This "instrument" periodically indicates that the test is done when, in fact, it is not. This is a glitch probably in the software. The manual rotating knob is not adequately de-bounced which leads to much manipulation of the knob to adjust desired values. This is a very crude mechanical/programming implementation that any programmer would easily avoid. I would only recommend this instrument to my worst enemies.

As a standalone load bank this unit is great, I bought it for the battery discharge software and eload software which is old bugy and never really works right even after the blast to the past of setting up comm ports, parity, and baud rates.

The 3710a offers features costing >=3x more on competitive units. OEM is Array, a Chinese company founded by Taiwanese engineers, so the quality is surprising higher than typical China branded gear. Its also sold as the Gossen-Metrawatt SSL150, as well as lesser brands like CSI, IWH, Protek and Tekpower, often with the model number 3710a imebbed somewhere. Gossen's model suggests they rated this product well enough to put their name on it, and my personal evaluation supports that analysis too. Its compact and portable, easy to run tests on supplies while in the field.ProsI confirmed many of its published specs and features through my tests, I ran it on various modes at 90W, over 1 hour, finally load tested it for over 20 hours at 130W. It has 3 modes: constant power, current, and resistance. You can program 10 step sequences in each mode to model variable load conditions with fastest speed of 1 sec per sequence, but you cannot mix modes, e.g. no CC switch to CR switch to CP etc. The slew rate during transition is fast, I haven't measured it fully but its at >= 2A/100ms. With software, you can sample from 100ms to seconds, the software can be set faster than 100ms but the data collection rate is unreliable. The internal power limit is actually set to 200W.It ships will all accessories needed except high current test leads. The serial-USB converter has bright LEDs that flash proportionate to the baud rate. Its very helpful feedback on data status if you use their bug ridden softwareCalibration procedures are available and easy to DIYThe communication protocol is documented to allow users to write their own interface softwareThere is a driver available for LabviewMaterials and build quality is surprisingly high. Array's other products have not been as well built Tekpower TP3646A Programmable & Variable High-Precision DC Power Supply 0-72V @ 0-1.5A with USB Connection. The 3710 and its sister 3711, have essentially no bad reviews and have been around since 2002.ConsIt has no constant voltageIt has no programmable "transients", step changes in us instead of seconds, nor programmable slew ratesIt uses soft keys, no tactile feedback, so a beep is helpful, but my unit screeches rather than beeps at times. This is likely a defective piezo element but its not easy to replace as its integrated into of a moduleThe rotary switch is too sensitive, you can jerk it and it will be read as valid motionNo remote sensing, voltage drops across cabling in high currents have to compensated forThe faceplate plastic is yellowing from age, and my unit was NIB. It seems to have languished in inventory since it was manufactured in 2010.The software is best collecting current, voltage, power, and resistance data over time. However, it has too many other bugs to list here. Its best to control the 3710a from the front panel and use software for collecting data only, so the much smaller 'discharge' software downloadable from the Array website is good enough compared to the full suiteIt cannot save to CSV but it will send data only to Excel. Software feedback is unreliable, you must check the USB converter LED status lights and the 3710a LCD to insure transmittal of data or command execution. The tiny gauges are set from zero to maximal value but are not re-scalable or re-sizeable, so when using the low end of the scale, say less than 10V or 1A, its barely viewable.SAFETY: the unit is not CE nor safety organization certified, like TUV or UL. Many big name e-loads aren't either, at most its CE. If Gossen-Metrawatt sells the model, it suggests their engineers have evaluated safety positively, but there are no official tests. I've done my own due diligence and find it safe, too.Conclusion:Constant current, power and resistance tests are common basic dc supply parameters, so if these are your only need, the 3710a is cost effective and capable. Typical lab bench eloads begin near $500 BK Precision 8540 Compact DC Electronic Load, 150W, 30A, 60Vand this model has more capability. The 3710a rates 5 stars for hardware living up to its spec sheet, but -1 star due to the software and uncertified safety limits.