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Customized power distribution increases productivity and safety in electronic product development

Tue, 11/19/2013 - 12:30pm
Greg Willits, Software Development, Marway Power Solutions

Electronics equipment development generally includes one or more of design verification testing, reliability testing, and product characterization where hardware behavior is studied and documented.

Design verification testing (DVT) in electrical and electronic systems is the process whereby the behavior of circuits is examined step-by-step to validate that actual behavior matches the original design intent. Reliability testing examines the ability of the product to yield desired behavior while under known working conditions to verify product longevity. Both forms of testing focus on discrete pass or fail results. Characterization differs from testing in that its goal is to understand how a product behaves under specified conditions. There is no pass or fail, but rather a gathering of data which can be used to determine future design objectives, or serve as a reference for future troubleshooting or failure analysis.

For electrical systems, testing and characterization often require the application of various power sources and/or workloads.

    • Multiple different power sources may be required to validate planned product options

    • Power sources with on-the-fly variability may be required to simulate unstable field conditions

    • Power inputs may need to be randomly dropped and reapplied to simulate power loss

    • Power ranges may need to be exceeded to verify equipment response and safety

    • Power loads may need to be varied to validate desired working ranges

Each of these scenarios introduces testing complexity in which issues related to safety, productivity, and test validity can be raised (figure 1).

A power distribution system with remote outlet and connector switching and otherwise customized to the needs of the tested product, can improve safety and productivity, and help ensure valid data collection (figure 2).

Improved test safety
For some applications, safety alone is a sufficient reason to encapsulate all power switching. It’s a simple proposition: high voltages and/or high currents are dangerous, and the less often they have to be manually handled the better.

Another area of test safety includes the coordination of local vs. remote control. Off-the-shelf systems offering remote control often do not include local overrides. Such systems are intended for full-time remote duties. Product testing can involve a mix of hands-on work and remote work, and power distribution must have the ability to locally disable remote control to ensure the safety of people during hands-on work.

Improved test repeatability
Most tests must be repeated several times to assure observed behavior is consistent. Characterization also requires repetition with control over multiple variables. Modern testing and characterization often involves automation to minimize variability and coordinate multiple variables. Power distribution is no exception. The ability to programmatically enable and disable power, switch between power sources, or switch between loads in coordination with specific test conditions, improves repeatability which improves test data quality.

Improved test productivity
Encapsulating multiple power inputs and loads into a single system, especially one with programmatic switching control, ultimately offers advantages in productivity. We’ve identified safety as one reason to avoid manual rewiring, but for some types of equipment, the time factor alone in waiting for rewiring of equipment can be a source of lost time and increased cost to the project.

Even for connections which do not have a personnel safety risk, there’s potential for equipment risk. Product prototypes may forego the normal integration of power supplies, voltage regulation, or other power normalization in order to characterize behavior with raw or variable power sources directly connected to circuitry inputs. This may require the coordination of several internally connected, and differing power inputs. Miswired or misconfigured setups could damage the product.

As mentioned, tests are often repeated to determine consistency. They’re also repeated under various environmental conditions, after firmware updates, corrective hardware patches, and under various power conditions. This repetition, often over months of testing and involving numerous people, magnifies seemingly small losses of productivity.

Pre-wiring all sources and test loads to a power distribution unit with configurable local switching, or better yet programmable switching, eliminates the time and cost of frequent manual rewiring, and the costs of occasional wasted tests or equipment failures caused by miswiring.

Programmable remote switching in particular offers the greatest productivity gains for automated testing. Including power configuration as part of the automation reduces setup time, improves the test protocol, and improves the data collected.

When programmable switching is integrated into the test power distribution system, multiple inputs and outputs can also be coordinated with single switch changes to ensure correct routing of complex configurations.

Switching is not necessarily limited to power conductors. Since the PDU would already be offering switching capabilities, non-power-related signals could be included in the switching and configuration routings. For example, the interconnects between modular subsystems could be routed through the PDU, and have dedicated switching, or be switching in coordination with power source changes.

PDU optimization
Much of the point-of-use power distribution landscape has become commoditized, and simple cases of one input with multiple uniform outputs are well served by commodity products. However, many applications, including those of product development and testing, can require more tailored solutions (figure 3).

Having a power distribution system optimized to the application means the system can address details which off-the-shelf products typically don’t such as:

    • More diverse configurations of circuits

    • More complex input/output configuration dependencies

    • Mixed sources of AC and DC inputs from facilities or integrated conversions

    • Integration of advanced features such as EMI and/or RFI filtering

    • Unlimited selection of wiring connectors

    • Implementation of standards for industrial, defense, or other specialized environments

    • Overall integration for reduction in space, interconnect wiring, and even cost

Summary
Electrical and electronic product development involves a great deal of repetitive testing, and many products require dynamic power conditions during testing. Frequent manual re-wiring introduces concerns about safety, productivity, and even test data validity.

Regardless of whether safety or productivity factors offer the most benefit, it may be worth considering whether your product testing could be improved with a customized power distribution solution.

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