Are We Grounded?

BACKGROUND:  The LAW Melter Electrode Power supply was designed to provide single-phase AC output to the melter electrodes with a maximum voltage of 321VAC, a maximum current of 12,302A and a maximum power of 1430KW. The power supply utilizes the ACS800-LC series liquid cooled IGBT-based inverters to convert the power from AC to DC back to AC. The Inverter Supply unit (ISU) contains the incoming/supply inverter modules to convert three phase AC voltage into a DC-link reference voltage, that is provided to the Inverter units (INU) and inverted back into a variable single-phase AC output voltage. On the load side of the INUs, a sine wave filter manufactured by CTI (100uH inductor, 300uF capacitor, 100mOhm resistor) is utilized to reduce the harmonics produced from the non-linear load of the inverters.

Objectives

RESOLUTION CONCEPT:  The WTP Project has prepared a conceptual design for an alternate ground fault detection system.  The primary objective for this team is to model and test this proposed solution.  The team will design and construct a model to simulate a ground fault.  The simulation must include the ability to evaluate changes in the resistive loads of the glass pool in the melter.  A secondary objective, is to evaluate changes to proposed model, evaluate alternative configurations, or the use of commercially off the shelf products for ground fault detection.  A final report will summarize the results to of the simulation(s) of the conceptual design, as well as any other designs considered.  The final report, model/simulation files, and any other documentation developed as part of this project will be provided to Project Sponsor.   

  • Capstone team members must be U.S. citizens or eligible to work in the U.S.
  • Capstone team members must sign a Hanford Tank Waste Treatment and Immobilization Plant (WTP) Non-Disclosure Agreement to protect the information that is owned by the U.S. government.
  • All Intellectual Property related to this project is owned by the U.S. government.
  • Capstone team members will be encouraged to travel to Richland, WA, meet the Engineering team responsible for this project, and tour the facility where this equipment is located.
  • Capstone team members will be expected to participate in a weekly, 1-hour meeting with Project staff to discuss the state of their work as well as issues, and results.

Motivations

PROBLEM:  The power supply is required to have a ground fault detection system to monitor the output circuits of the power supply and alarm. The existing ground fault monitor is an insulation resistance monitoring device for ungrounded AC systems. The device superimposes a pulsating AC measured voltage on the system and monitors the circuit for an insulation fault between the ungrounded system and ground closing the measuring circuit. The measured current value is used to calculate the insulation resistance which is indicated on the display and provides local HMI alarm.
The monitor has been ineffective measuring across the molten glass pool. As a compensatory measure, manual readings are taken from power quality meters on the output transformers to monitor voltage differential for alternate indication of ground faults in the system. An automated detected system is needed as the power supply is always running to maintain melter glass pool temperature.

Qualifications

Minimum Qualifications:

Electrical Engineering

Ground Fault Detection

Ungrounded Systems

Preferred Qualifications:

N/A


Details

Project Partner:

Peter Benson

NDA/IPA:

NDA Required

Number Groups:

1

Project Status:

Accepting Applicants

Website:
https://www.hanford.gov/page.cfm/WTP
Video:
https://www.youtube.com/watch?v=NOcpthpN3g0
Card Image Capstone