RoadTest: R&S NGP814 Power Supply
Author: waleedelmughrabi
Creation date:
Evaluation Type: Power Supplies
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: Regatron TopCon programmable PSU, Keysight E36200/E36300.
What were the biggest problems encountered?: Channel adjustment calibration failed. Noticeable mismatch in parallel mode. High current overshoot when current level rises.
Detailed Review:
Introduction
I would like to first thank element14 and R&S for this opportunity to test and review the NGP814, I have enjoyed the learning curve while doing the road test.
I applied for this test hoping to investigate and experience the capabilities of a power supply in this range, especially the arbitrary function generator combined with various possible series and parallel combinations.
Power supplies I have used in the past were either on the low end or high end application specific devices. Most low end power supplies offer basic features and don't provide logging or automated testing, however this was not what they are designed for. Application specific programmable power supplies like solar array simulators are designed with a specific application in mind, bulky, and much more expensive than general purpose devices. In the case of the NGP814 it is right in that sweet spot in between, I think the selling point is that it combines various devices into one.
Pros:
- Four galvanically isolated channels: this offer a very versatile setup capable of covering a wide range of voltages and currents within the 800W rated power.
- Touchscreen and easy to use interface.
- Supports LAN, GPIB, USB connections.
- Logging.
- Arbitrary function generator.
- Supports SCPI commands.
- Compact size considering its rated power.
Cons:
- Quiet big and heavy for a benchtop device, ideally needs to be rackmounted.
- PC software does not cover the features the device offers.
- Documentation is not intuitive.
- Rear connectors have a relatively small pitch considering the wire gauge needed for high power use cases.
- High current overshoot.
Unboxing & First impression
The device arrived safely and functional, which is surprising considering the state of the box which seems to have been thrown around during transit. the box contents are:
Equipment used
Preparations
To avoid any noise coming from mains and for safe operation, all devices are powered through AC power conditioner/distribution units "Samson PowerBrite PB10 Pro".
Unlike what you find in many other test and measurement equipment, the rear inputs are directly connected to the front banana plug inputs with no need for any buttons to be pressed to switch between them, my only comment about the rear input is to be careful of short circuit, got to make sure the cable sleeve is reaching inside the slot and bare wire is fully inside the contacts. This was tricky because I am using high current rating wires with a 4 mm² core cross section, especially when using the device in series and parallel configurations.
To work with high voltage and current, cables and test leads needed to be rated accordingly. Usually there is some tolerance margine but not recommended. The cables I am using are rated for up to 55A, which covers the tests I am doing.
Cables specifications:
4 mm², single-core, Black, 1m
Cross section: 4 mm²
System voltage: 1000 V
Rated current: 55 A according to DIN VDE 0298 part 4
Operating temperature range: -40 – 120 °C
Road Test
For this road test I decided to separate each test in a blog to make it easier to navigate. I have seen some other road tests done this way and found it much easier to go through the full report and find content.
Part 1: Overview, Firmware, and Calibration
Part 3: Static/Dynamic Load Testing [Updated: 10 Jan 2021]
Part 5: Curve Sequence and Inverter Testing (Delayed until inverter is sent back from manufacturer due to a fault in inverter)
Summary
The device weighs around 10kg, and for that the thin cardboard used in packaging could barely hold it in. A higher grade thick cardboard and nylon straps can provide better protection. The photos in the "Unboxing" section of the review show that the box was bent due to the heavy weight of the unit.
Overall the device is very well built, noise levels are minimum, and designed to give flexibility in automated testing. Having four galvanically isolated channels can be very useful, when combined the device can achieve higher voltages and currents, and when separate they can be used to test multiple devices at the same time. One more important advantage of having four channels is that in the design stage, you can supply a prototype with various voltages at the same time (i.e. in automotive applications: 5V,12V, or 48V), this can help the designer focus on functionality and deliver a POC faster then revisit the power circuit design at a later stage.
One issue that burnt the test equipment fuse, was the current overshoot shown in Part 5.
A feature that can add a lot of value to the NGP800 series is "connection mode" (independent, series, parallel) where the device can automatically lower mismatch in parallel mode and internal switching can connect the channels contacts to eliminate the need for a bunch of external wires and avoid mismatch in cable length.
Yes I would have preferred to see more spacing between the rear connectors, and a better PC software, but my conclusion is that the pros overcome the cons. A lot of horse power and various features within a very good price range for a power supply of this calibur.
