Author Topic: Recalibrating Array DC Electronic Load 3715A??  (Read 516 times)

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Offline marmelade

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Recalibrating Array DC Electronic Load 3715A??
« on: September 18, 2018, 05:37:58 pm »
Around two years ago I bought a DC Electronic Load from Array. Its the "basic" 3715A model, which I beleive is also branded and sold by Gossen Metrawatt.

Haven't used it very much until now. To be honest, I am quite disapointet with the accuracy/performance of the instrument. In CC-Mode, set at 0A, it sinks roughly 60mA. The voltage-readout seems reasonable accurate, but the current readout is absolutely off (i.e. showing 1.2A whilst sinking 0.5A).

Is anybody aware of a calibration/adjustment procedure for these instruments?? What can I do?

 

Offline bicycleguy

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Re: Recalibrating Array DC Electronic Load 3715A??
« Reply #1 on: September 18, 2018, 09:48:44 pm »
Is that in the 3A or 30A Current range?  30A would be in spec, 3A out.
 

Offline marmelade

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Re: Recalibrating Array DC Electronic Load 3715A??
« Reply #2 on: September 19, 2018, 08:31:54 pm »
I am currently not able to set a particular range. The manual is stating the existance of a low and high range but the UI does not show anything alike.

Just this evening I tried establishing a remote connection via RS-232 in order to set the range remotely  (yet unsuccessful). I am a bit confused, the manual mentiones DSR/DTR flow control but on the very same page only TX+RX+GND are connected....? Does the number of bits include or exclude the stop bits? Has anybody figured out the proper parameters yet?

A quick test with a DMM hooked up to the lab supply: (PSU-Voltage = 10V)

Current(DMM) [A] |  Setpoint(load) [A] | Readback(load) [A] | Readback(load) [V]
 0.060                   | 0.0                         | 0.357                       | 10.04
 0.160                   | 0.1                         | 0.457                       | 10.04
 0.362                   | 0.3                         | 0.658                       | 10.03
 0.563                   | 0.5                         | 0.860                       | 10.03
 1.065                   | 1.0                         | 1.363                       | 09.99
 2.070                   | 2.0                         | 2.370                       | 09.93
 2.570                   | 2.5                         | 2.873                       | 09.90
 2.977                   | 2.9                         | 2.363                       | 09.88
 3.077                   | 3.0                         | 3.060                       | 09.88
 3.580                   | 3.5                         | 3.560                       | 09.85
 3.980                   | 3.9                         | 3.960                       | 09.82

Above 3A, the initial offset remains, but the readback values seem ok. Below the deviation is obvious. Is there a possibility to manually adjust the current-sensing?
 


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