Discovery MR750w and SIGNA™ Architect T 3.0T System Service Methods
5690002-2EN Revision 4
Object ID: 00000018WIA3055D630GYZ
Topic ID: id_19633182 Version: 5.2
Date: Feb 14, 2022 4:09:17 PM

Applying LOTO - HEC

Prerequisites


Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
1	-	10 minutes	-


Tools and test equipment
Item	Quantity	Part number	Manufacturer
RED Logout Tagout Lock with Each Lock Uniquely Keyed	3	5451778	-
Multi-Locking Device (if multiple service personnel are involved)	1 to 3 (up to three may be necessary if the valve LOTO devices support only one lock)	46-194427P313	-
Red Warning LOTO Tag	3	46-194427P322	-
Digital Voltmeter (DVM)	1	46-194427P284	-
Ball Valve LOTO Device	2	5372868	-


Safety
Before working in any GE Healthcare MR suite or performing any GE Healthcare service procedure, you must: Have read and understood all hazard conditions and safety requirements in the latest revision of the GE Healthcare MR Service Safety Manual (5452735). Have successfully completed all relevant GE Healthcare Environmental Health and Safety (EHS) courses (or for non-GE employees, equivalent workplace training courses). Comply with all site-specific training and workplace safety requirements. If you have any safety concerns at any time, do not begin work or immediately stop work and move to a safe location. Immediately contact your supervisor or site safety officer for instructions on how to proceed.

Warning

Electrocution hazard

High voltage present.

Use proper LOTO procedures before servicing and/or maintaining.

About this task

Prior to doing servicing and/or maintenance work on the Heat Exchanger Cabinet (HEC), the steps in this Lockout/Tagout (LOTO) procedure must be completed by a LOTO-authorized GE Field Engineer (FE). Completing all steps in this procedure ensures a safe environment, and avoids equipment damage when working on these parts.


Affected by LOTO
Name of equipment	Number of locks	Titles of employees authorized to perform LOTO	Titles of affected employees	How to notify
HEC Cryocooler compressor	1 per GE field engineer (FE)	GE Field Engineers	Hospital personnel	Verbal, posted signs

Note: The following table describes the type, location, and magnitude of energy to be LOTO’d.


Energy Source	Yes	No	Location of Energy Isolating Means	Magnitude of Energy
Electrical	x		Main Disconnect Panel (MDP) Circuit breaker panel	380 to 480 VAC
Pneumatic		x
Hydraulic		x
Gas/Water/Steam		x
Chemical		x
Mechanical Motion		x
Gravity		x
Springs		x
Thermal		x
Stored Energy	x
Air Under Pressure		x
Oil Under Pressure		x
Water Under Pressure	x		Facility water valves at top of HEC and MDP circuit breaker panel	6.0 Bar (87 psi) Input 5.7 Bar (82.8 psi) Output Gradient Coil (GC) 5.0 Bar (80 psi) Output Power, Gradient, and RF (PGR) Cabinet
Gas Under Pressure	x		Valves on ends of cryocooler helium lines – valves close automatically when disconnected
Steam		x
Other		x

Topic ID: id_SL1784262-1162789

Types of equipment and/or methods selected to dissipate or isolate stored energy

About this task

None required.

Topic ID: id_SL1784263-1162789

Type(s) of equipment and/or method(s) used to ensure disconnection(s)

About this task

A personal lock and tag per Field Engineer (FE) at the site working on the de-energized equipment at the time of LOTO.

Procedure

Apply LOTO to the MDP:

Notify affected personnel that LOTO will be applied.
On the front of the HEC, look at the variable speed drive displays to visually make sure that the power is on. If power is off, proceed to Step 1.e.

Figure 1. HEC variable speed drive displays
Note: Powering off HEC without first powering down pumps from VFD can put the VFD at risk of damage.
Toggle off the pumps and blower with the PLC Signal Box keypad as follows:
- Blower: Press and hold the up-arrow ( ^ ), and press F1
- Gradient Coil Pump: Press and hold the up arrow ( ^ ), and press F2
- Power Electronics: Press and hold the up arrow ( ^ ), and press F3
  Figure 2. PLC signal box
Make sure the VFD LEDs read zero before proceeding.
Turn off all five circuit breakers on the HEC power box. The circuit breakers are located above the variable speed drive displays.

Notice

Loss of power

Powering off the HEC circuit breaker will cause the Cryocooler Compressor to also lose power.

Make sure the HEC downtime is minimized to avoid boiling off cryogens.

Put Magnet Monitor in Service mode to prevent logging of false RFS case events during this time.

Note: If the customer has supplied the MDP, see the MDP manual for information about LOTO for the HEC circuit breaker.

At the front of the MDP, move the HEC circuit breaker to the OFF position and apply LOTO.

Make sure all energy is dissipated. Carefully remove the four thumbscrews securing the HEC power box front cover and remove the cover.

Figure 4. Location of screws on HEC power box
Make sure voltage is removed by testing the line-to-line voltage at the top of the breaker points.

Figure 5. Terminal points of HEC power box
Replace the power box front cover.

Apply LOTO to the HEC shut-off valves:
1. Prepare for shut down. Check with the facility owner to determine the proper shutdown method for the chiller.
2. Shut off both the facility return and supply valves by turning the handle to a 90º angle.
3. Apply LOTO device to both the return and supply valves.
  
  Figure 6. LOTO installed on return valve
  
  Figure 7. LOTO installed on supply valve
4. Drain the fluid between the return and supply lines. Refer to Coolant Draining in the Service Methods manual for the system.
5. Make sure there is no water draining from quick disconnect and pressure in the line is relieved.