Editor's Choice


Reliable grounding methods for high-voltage power supplies

26 May 2021 Editor's Choice Power Electronics / Power Management

Proper ground connections between a power supply, AC mains input and the application’s load are essential for stable, reliable operation, but for high-voltage supplies this is even more crucial.

Proper ground connections between a power supply, AC mains input and the application’s load are essential for stable, reliable operation, but for HV (high voltage) supplies this is even more crucial. This is due to the large stored energy in the HV output circuits and the higher possibility of an arc discharge between the HV output and ground within the application’s load and connections. There are three major ground signal paths in a HV power supply driven system: AC mains input sources, control signals and the HV load return. Let’s take a look at each one.

AC mains

All AC connectors and cords are required to contain a safety ground, which is typically an additional conductor in the line cabling which is the same gauge as the AC feed wires. This is intended only as a safety ground should the chassis of the power supply become disconnected from ground and should never be used to connect signal or load returns. This is also always a part of the line connection system as required by all standard wiring codes and standards.

Interface signals

These are the returns for any external signal interfaces such as programming, monitoring, enabling and interlock. The returns of all these signals should be connected to the common of the power supply and not directly to ground. The common inside the supply is connected to ground at the proper point to ensure that no transient voltages or RFI appear on the signal interface.

Multiple common connections are provided on the signal interface connectors of the power supply for this purpose. If the external interface cabling employs shielded or coaxial wires, then the shield of the wires must be separate from the common return and should be connected only at the power supply end to ground. A ground pin is provided on the interface connectors.

Load return

The HV load return, besides carrying load return current, also carries high peak discharge currents caused by arc discharges within the application’s load. When a HV power supply is quickly discharged, the stored energy inside the power supply is discharged through an internal limiting resistance. Since this resistance cannot be very high without degrading specifications or dissipating excessive power and heat, the peak currents are typically high, although of short duration.

This peak current flows through the load return wiring back to the energy source in the supply. Since these are fast rise-time transient currents, they can produce a significant voltage drop across the return wire if it is not carefully designed and returned properly. A large ground stud (designated E1 in Figure 2) is provided on all XP Glassman supplies for load return connections.

Figure 1 shows the situation that occurs when an arc discharge occurs. The high di/dt transient current flows through the return circuit stray inductances and even a very small wiring inductance can produce significant voltage spikes. In order to minimise these transient spike voltages:

• The load return should be a heavy wire connection or braid directly connected to the ground stud on the power supply chassis. It should be as short as possible and never coiled up. The load return should not be tied to house ground or any other ground return at the load end.

• A heavy wire connection should be made directly between the chassis ground stud and house ground. The AC mains ground should never be relied on as the only chassis-to-house ground connection and should never be a part of the grounding scheme. Mounting the load and the supply on a heavy ground plane is the best configuration but this is often not practical.

• House ground is typically the building frame, electrical conduits or water pipes.

Grounding guidelines

Figure 2 shows the recommended grounding arrangement. The signal interface wiring should be shielded if possible, with the shields connected to the power supply ground at the signal connector. A chassis ground pin is provided on the signal interface ‘D’ connector for this purpose. The signal interface returns should be connected to the common return pins on the interface ‘D’ connector and not the chassis or house ground.

The shield of the HV cable should not be terminated at the load end but should be cut off and covered. The recommended wire gauge for the load return wire is a function of the type of load but should generally be heavier than #6 AWG. Finally, the interface signal commons should be isolated from ground.


Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Ultra-portable spectrum analyser
Vepac Electronics Test & Measurement
The PXN-400Z from Harogic is a handheld spectrum analyser covering a frequency range of 9 kHz to 40 GHz with a 100 MHz analysis bandwidth.

Read more...
Versatile 3-in-1 instrument
Vepac Electronics Test & Measurement
The ARB Rider AWG-2000 is the cost-effective and powerful two or four channel arbitrary function generator and two or four channel arbitrary waveform generator with advanced sequencer functionality.

Read more...
Enhance SiC device efficiency using merged-pin Schottky diodes
NuVision Electronics Editor's Choice Power Electronics / Power Management
Silicon carbide (SiC) has advantages over silicon (Si) that make it particularly suitable for Schottky diodes in applications such as fast battery chargers, photovoltaic (PV) battery converters, and traction inverters.

Read more...
What is Wi-Fi HaLow and why choose it for IoT?
iCorp Technologies Editor's Choice Telecoms, Datacoms, Wireless, IoT
Wi-Fi HaLow introduces a low power connectivity option that, in contrast to other Wi-Fi options, offers greater range of approximately 1 km, which opens up a raft of IoT use cases.

Read more...
Simple battery charger ICs for any chemistry
Altron Arrow Editor's Choice Power Electronics / Power Management
The LTC4162 is a highly integrated, high voltage multi-chemistry synchronous monolithic step-down battery charger and PowerPath manager with onboard telemetry functions and optional maximum power point tracking.

Read more...
From the editor's desk: Is the current AI really what we want?
Technews Publishing Editor's Choice
The companies that develop LLMs need to change direction and concentrate on freeing up our time, not so that we can have more time to do the tasks we don’t want to do in the first place, but rather to allow us more time to do what we love.

Read more...
EEPROMs for industrial and military markets
Vepac Electronics DSP, Micros & Memory
Designed to ensure the data retention and the secure and safe boot of digital systems, the memory product line includes small and medium density EEPROMs from 16 kb to 1 Mb.

Read more...
When it comes to long-term reliability of RF amplifier ICs, focus first on die junction temperature
Altron Arrow Editor's Choice Telecoms, Datacoms, Wireless, IoT
When considering the long-term reliability of integrated circuits, a common misconception is that high package or die thermal resistance is problematic. However, high or low thermal resistance, by itself, tells an incomplete story.

Read more...
ICs vs modules: Understanding the technical trade-offs for IoT applications
NuVision Electronics Editor's Choice DSP, Micros & Memory
As the IoT continues to transform industries, design decisions around wireless connectivity components become increasingly complex with engineers often facing the dilemma of choosing between ICs and wireless modules for their IoT applications.

Read more...
Why bis means business for LTE Cat 1 IoT connections
NuVision Electronics Editor's Choice Telecoms, Datacoms, Wireless, IoT
Tomaž Petaros, product manager IoT EMEA at Quectel Wireless Solutions explains why the market for Cat 1bis IoT connections is getting busy.

Read more...









While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.




© Technews Publishing (Pty) Ltd | All Rights Reserved