Introducing the DCShortCUT!
Updated: Jan 21, 2021
Wednesday Write-up: Diodes Part 4
Testing Complex DC Power Systems using reliable and repeatable methods
We've spent the last few weeks giving you a taste of the basics of a diode. We also described DC diode protection arrangements, and what it can and can't protect against. This week, we talk about proving these systems safely and reliably using OneStep Power's DCShortCUT.
When OneStep Power first started to review the need for a technology to prove the safety and reliability of the cross-connected DC power supplies aboard Dynamically Positioned vessels, the first step was to ensure the DC protection arrangements were suitable and sufficient for all conceivable fault cases. New circuit protection devices were identified for arrangements where sufficient protections weren't in place. (Mainly this was a DC arrangement where only diodes were used, and which a diode-load side short circuit would result in complete system loss, as we described here last week.)
These new circuit protection devices provide the final layer of protection for multiple power supply DC distribution networks. The short circuit fault cannot propagate beyond the electronic circuit protection devices, ensuring the rest of the system remains operational.
Electronic Circuit Protection Device in action!
There are a number of ways to resolve the cross-connection protection issues, including design changes and equipment substitutions to incorporate electronic circuit protection within the system.
But still, the question remains, how do you prove your cross-connections won't propagate a fault?
Introducing the DC Cross-connection Short Circuit Under Test
The DCShortCUT is OneStep Power's solution for 24V DC cross-connection testing. The device is installed temporarily to multiple points within the system under test. Once installed, the test program can be quickly executed, with all data at all points captured for comparison.
DCShortCUT basic arrangement
Though testing of the short circuit downstream of the diodes is the highest risk test, OneStep Power has developed a technology to allow all potential failure modes in the 24V DC arrangement to be tested from one device. Tests which are performed as part of this package are:
Load test of power supply 1
Load test of power supply 2
Overload test of power supply 1
Overload test of power supply 2
Short circuit on power supply 1
Short circuit on power supply 2
Short circuit on power supply 1 & 2
Short circuit on load-side of diode
Earth fault on power supply 1
Earth fault on power supply 2
Earth fault on power supply 1 & 2
Earth fault on load-side of diode
Overvoltage power supply 1
Overvoltage power supply 2
Overvoltage of load-side of diode
Loss of power supply 1
Loss of power supply 2
Connection, the full suite of testing, and disconnection takes approximately 1 hour for panels in the configuration shown above.
The DCShortCUT has been successfully deployed in-field, demonstrating the reliability of the 24V DC system, and finding potential failure points.
The key benefits of performing testing using the DCShortCUT include:
Removal of personnel from testing areas
Repeatable tests with clear pass/fail criteria
Vessel protective functions remain “as-is”
Invisible to the vessel
Real fault responses delivered without system damage
Before deployment of the DCShortCUT, OneStep Power can bench-test a sample of your specific power system quickly and efficiently, to identify possible failures prior to deployment, giving you a robust, reliable, and repeatable solution.
Bench testing in OneStep Power's Houston facility