• Topic ID: id_12373405
  • Version: 1.9
  • Date: Jul 5, 2019 10:03:33 PM

XRMw Cable Busbar Replacement

Prerequisites

Table 1 Personnel requirements
Required persons Preliminary requirements Procedure Finalization
2 30 minutes 5 hours 2 hours
Table 2 Tools and test equipment
Item Quantity Effectivity Part number Manufacturer
PPE: non-magnetic safety shoes, safety glasses, and gloves 1 - - -
Arc Flash PPE 1 - - -
Non-magnetic Tool Set 1 -

5112581

 -
Non-magnetic Torque Wrench 1 -

5534134 or 5537507

 -
Table 3 Consumables
Item Quantity Effectivity Part number Manufacturer
Blue Loctite 243 (check expiration date) 1 -

5415261–2

 -
Alcohol wipes As needed - - -
Black Sharpie pen 1 - - -
Table 4 Replacement parts
Item Quantity Effectivity Part number Manufacturer
XZ XRMw Busbar 1 -

See FRU Manual

 -
Y XRMw Busbar 1 -

See FRU Manual

 -
Table 5 Safety
  • danger
  • Strong Magnetic field!
  • ferrous materials can become dangerous projectiles in the presence of the magnetic field produced by the magnet.
  • Do not bring any ferromagnetic tools or equipment into the magnet room.
  • caution
  • ELECTRICAL SHOCK HAZARD!
  • Contact with the connectors leading to an energized power supply can cause electrical shock.
  • Follow lockout/tagout (LOTO) procedures while performing services to electrical connection components.
Table 6 Required conditions
Condition Reference Effectivity

At least one individual performing this procedure must have taken training course GEHC-TECH-AMOL-CT530-01_CURR.

- -

Overview

This procedure describes the replacement or installation process for the eXtreme Resonance Module Revision W (XRMw) busbars.

The system has two busbars: the XZ busbar assembly and the Y busbar assembly. Typically, only one busbar is replaced at one time.

Figure 1. Y and XZ Busbars

Getting Started

Procedure

  1. Order the non-magnetic torque wrench before starting this procedure.
    2. Notice Image
    • caution
    • Follow all safety lockout/tagout procedures.
  2. Perform LOTO on the PGR PDU/gradient subsystem. See the MR Service Safety Manual, PN 5452735.
  3. Remove the patient bridge. See Bridge and Longitudinal Drive Belt Replacement.
  4. Remove the magnet enclosure rear end bell. Rear End Bell Removal and Installation.
  5. Move the rear pedestal away from the magnet to allow access to the busbars.
    note:

    Slack in the cables going to the rear pedestal should allow it to be moved back without disconnecting cables. However, it is possible that some cables may need to be disconnected.

Busbar Removal

Typically only one busbar is replaced at a time. The removal and installation processes for Y and XZ busbars are the same. If a different instruction is required, the instruction is labelled specifically for Y or XZ.

Procedure

  1. note:

    DO NOT remove the clamps on the busbar leads.

    Remove M10 nuts and Nord-Lock washers that secure the busbar lugs to the coil. Slide the busbar terminal lugs off of the studs at the coil.

    Discard the Nord-Lock washers and stainless steel flange nuts.

  2. At the top of the busbar, remove screws and the plastic cover from the busbar.

    • (For Y busbar) Remove two screws.

    • (For XZ busbar) Remove three screws.

  3. At the top of the busbar, remove the four M10 brass nuts and Nord-Lock washers that secure the gradient power cables to the busbar terminals. Slide the gradient power cable lugs off of the studs on the busbar.

    • (For Y busbar) Remove four nuts and Nord-Lock washers. See Figure 2.

    • (For XZ busbar) Remove eight nuts and Nord-Lock washers. See Figure 3

    Discard the Nord-Lock washers.

    Figure 2. For Y Busbar: Disconnecting Gradient Power Cables

    Figure 3. For XZ Busbars: Disconnecting Gradient Power Cables - Magnet End

  4. Remove the nuts and washers that secure the busbar the gradient coil.

    • (For Y busbar) Remove ten nuts. See Figure 4.

    • (For XZ busbar) Remove six nuts. See Figure 5.

    Discard the brass nuts.

    Figure 4. Y Busbar Mounting Points

    Figure 5. XZ Busbar Mounting Points

  5. note:

    Observe the following:

    • DO NOT lift the busbar assembly by holding the leads.

    • (For Y busbar) Make sure the G-10 (glass-reinforced) spacers and rubber washers remain on each mounting stud.

    The busbar assembly can now be removed from the magnet.

Busbar Installation

Typically only one busbar is replaced at a time. The removal and installation procedure for Y and XZ busbars are the same. If a different instruction is required, the instruction is labelled specifically for Y or XZ.

Procedure

  1. note:

    Observe the following:

    • Before installing the replacement busbar, inspect the surfaces that will connect the gradient coil and cables for oxidation. If the gradient copper surface is oxidized, clean the surface with a light abrasive pad.

    • DO NOT remove the clamps on the busbar leads.

    • DO NOT lift the busbar assembly by holding the leads.

    • Clean the magnet mounting stud threads with a non-magnetic brush to remove any remnants of thread-lock material.

      Hand thread a clean M10 nut onto the stud and check that the nut rotates freely. The thread should be free of high friction or locking spots.

    • Wipe the studs and the gradient coil terminals clean with alcohol to assure particle and dust removal.

    Slide the busbar assembly (with leads hanging down) onto the mounting studs.

    • (For Y busbar) The Y busbar has ten mounting studs.

    • (For XY busbar) The XY busbar has six mounting studs.

  2. Install a G-10 (glass-reinforced) washer on each stud. Apply one drop of Loctite 243 to the threads of each mounting stud. Then install a brass nut onto each mounting stud.
  3. Starting at the top and moving clockwise between mounting studs, hand-tighten each nut evenly. Again moving clockwise between studs, tighten one full turn (1/2 turn at a time). Stop when 2-3 threads are showing above each nut.

    Figure 6. For Y Busbar: Location of Brass Nuts

    Figure 7. For XZ Busbar: Location of Brass Nuts

  4. note:

    Observe the following:

    • Always use the new Nord-Lock washers that come with the FRU package. DO NOT reuse the old Nord-Lock washers.

    • Nord-Lock washers consist of two pieces, which are generally glued together. Always use a complete set with two pieces joined together in correct orientation. DO NOT use a separated single piece. If the Nord-Lock washers are separated, or the nuts are untightened, discard the washers and replace them with new Nord-Lock washers only. If new Nord-Lock washers are not available, contact the online center for further instructions.

    • Always shake Loctite bottle before use.

      Figure 8. Nord-Lock Washers

      1 Wrong (do not use separated washers)
      2 Correct
    Place a new Nord-Lock washer over the stud. Put two drops of Loctite 243 on the exposed thread.

    Do not get Loctite on the Nord-Lock washer. Hand-tighten the nut.

    Discard the old washers.

    5. Notice Image
    • danger
    • Death or serious injury!
    • make sure the torque wrench used is nonferrous.
    • Tool Kit 5534134 or 5537507 or other non-magnetic torque wrench should be used for the following step.
    Notice Image
    • notice
    • At a minimum, one person performing this procedure must have taken training course GEHC-TECH-AMOL-CT530-01-CURR.
    Notice Image
    • notice
    • Do not re-use Nord-Lock washers. If a nut must be replaced after the Loctite has set, you must remove the existing Loctite with a Scotch Brite pad and alcohol.
    Notice Image
    • notice
    • Torquing must be done within 10 minutes of applying the Loctite.
  5. Set the torque wrench to 25 ft-lbs or 33.9 Nm. Install 15 mm socket on the extension.
    note:

    Make sure that the arrow on the torque wrench is visible. If the arrow is not visible, the torque wrench will not “click” when the proper torque is reached.

    Figure 9. Arrow on Non-magnetic Torque Wrench

  6. Torque the nut in the direction of the arrow until the torque wrench reaches the break point.
  7. Using a Sharpie pen, place a line from the base of the stud to the nut.

    Figure 10. Stud and Nut Marked to Show Torque Position

    Item Description
    1 Black line on nut and stud to show torque position.

    Repeat this process for all stainless steel flanged nuts.

  8. Perform a second torque operation at each nut to confirm the proper torque of the nut.

    If the nut moved more than one flat from the original position, you must re-torque the nut a third time.

    If re-torqueing was required, re-mark the line on the nut and stud.

  9. Install the safety cover.
    1. Inspect the flame-retardant material (white cloth) for tears or internal damage. Replace safety cover if liner is damage. See FRU list for part number.
    2. Ensure the flame-retardant material (white cloth) is folded out around the edges of the safety cover. There should be no openings between the safety cover and the gradient coil.
  10. At the top of the busbar (after applying system cables), install new Nord-Lock washers, then brass nuts, onto the studs of each busbar.

    Use the torque wrench to tighten the nuts on the top of the busbar to 25 ft-lbs or 33.9 Nm. See Step 5.

  11. At the top of the busbar, install plastic cover with two screws to the busbar.

    • (For Y busbar) Two screws hold the plastic cover on the Y busbar.

    • (For XZ busbar) Three screws hold the plastic cover to the XZ busbar.

    Always ensure that the stud extends beyond the end of the nut.

    Figure 11. Installation Sequence of Terminal

    Item Description
    1

    Sequence for installing fasteners:

    1. Power cable lug

    2. Nord-Lock washer

    3. Nut
    note:

    Observe the following:

    Proper torque to the nuts holding the busbar lugs is critical to the long-term stability of the gradient subsystem.