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Message ID: 1782     Entry time: Thursday, September 13, 2018, 16:57
Author: Isaac Earle 
Category: North Hot-Cell 
Type: Development 
Module:  
Target/Number:  
Subject: NHC grounding and mili-ohm testing 

 The following equipment has been connected to the building ground located in the Target Hall by the TCS using 1/2" flat bonding strap:

  • NHC roof structure
  • NHC/TCS partition wall
  • NHC work table

The following equipment has been connected to the building ground by connecting to the work table inside the NHC using 1/2" flat bonding strap:

  • Air and gas supply line mounting bracket inside NHC
  • Receptacle box mounting bracket inside NHC
  • Diagnostic signal box mounting bracket inside NHC

 

The resistance between the following locations and the copper grounding plate located at the base of the NHCSA north wall were measured.  The resistance of the wire used was 258.10mΩ, and has been subtracted from the following results.

Measurements taken in NHCSA:

  • Control panel below viewing window (base plate of box): 4.67mΩ
  • Oil window frame (bare metal drain valve): 55.34mΩ
  • Left manipulator (ground plate near e-stop button): 73.46mΩ
  • Right manipulator (ground plate near e-stop button): 202.58mΩ
  • Air and gas supply line mounting bracket: 40.68mΩ
  • Diagnostic connector box: 12.15mΩ
  • Steel conduit for 110V supply to hot cell interior: 4.81mΩ

Measurements taken inside NHC:

  • Work table: 4.51mΩ
  • Pre-filter bolted to partition wall: 4.84mΩ
  • Table hatch lid: open load
  • Left manipulator thru tube: 515.8mΩ
  • Right manipulator thru tube: 342.0mΩ
  • Left manipulator (slave boot plate bolt): 885.9mΩ
  • Right manipulator (slave boot plate bolt): 1444.0mΩ
  • Grounding strap for air/gas plate: 4.84mΩ
  • Outside of SHV connector on diagnostic signal box: 4.56mΩ
  • Exterior of 110V electrical conduit: 3.88mΩ
  • Male Staubli connector for 1st gas line: 53.7mΩ
  • Welded stud for window cover panel: 6.06mΩ
  • Grounding strap for partition wall: 4.39mΩ
  • Roof structure (measured inside un-painted bolt hole): ~0mΩ
  • Stainless steel module flange: ~0mΩ

Dedicated grounding will be added in the near future for the oil window frame and the manipulator thru-tubes.  Testing will then be repeated for those items.

 

Dec 18, 2018 update:

The oil window frame and both manipulators (where they bolt to the thru-tubes) were connected to the building ground using 1/2" flat bonding strap connected at the cold side of each piece of equipment, and running to the grounded copper sheet located in the NHC service area at floor level.  The connection is made inside the electrical racks located directly west of the NHC operator area on the cold side.  This work was done by Travis Cave in October 2018.

Mili-ohm testing for these items has not yet been repeated.

 

Jan 14, 2019 update:

Grounding was added from the metal plate near the e-stop button on the master arm of both manipulators.  The same 1/2" flat bonding strap was used which was tied into other bonding strap which runns to the grounded copper sheet in the NHCSA.

Mili-ohm testing was repeated for the following items:

  • Oil window frame (bare metal drain valve):  13.6mΩ
  • Left manipulator (ground plate near e-stop button):  16.1mΩ
  • Right manipulator (ground plate near e-stop button):  16.5mΩ

 

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