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What This Guide Helps With
This guide helps troubleshoot the ACMains POWER FAIL alarm on a GE Healthcare Aisys anesthesia machine. This alarm indicates the system is running on battery because AC mains power has been lost, unstable, disconnected, or not detected by the machine.
Loss of AC mains power can affect how long the anesthesia machine can safely operate before battery depletion. If AC power is not restored, the condition may progress to low battery, battery empty, or system shutdown alarms.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
- Confirm whether the anesthesia machine is connected to an active patient.
- If the unit is in use, notify anesthesia staff immediately that the machine is operating on battery power.
- Verify that alternate ventilation and monitoring options are available if power cannot be restored quickly.
- Do not ignore the alarm during a case.
- Do not troubleshoot power connections in a way that disrupts active patient care.
2. Verify the Reported Alarm and Behavior
- Confirm the exact alarm displayed is ACMains POWER FAIL.
- Check for displayed text such as Plug in power cable. On battery.
- Observe whether the alarm occurs during startup, during a case, after moving the machine, after a facility power event, or intermittently when the power cord is touched or repositioned.
- Check whether the unit is operating on battery and whether the battery status is decreasing.
- Look for related battery alarms or missing AC power indicators.
3. Confirm the Power Cord Is Plugged In
- Inspect the power cord at the anesthesia machine and wall outlet.
- Verify that the cord is fully seated at both ends.
- Check for a loose connection, partially unplugged cord, damaged plug, damaged strain relief, or cord pulled tight.
- If the cord was loose, reconnect it securely and confirm whether the alarm clears.
4. Restore AC Mains Power
- Plug the machine into a known working hospital-grade outlet.
- If already plugged in, unplug and reseat the power cord if safe and appropriate.
- Confirm the outlet is not controlled by a wall switch or affected by a local power issue.
- Verify that the machine returns to normal AC power operation after stable power is restored.
5. Check the Wall Outlet
- Test the outlet using an approved outlet tester or approved facility process.
- Check whether other devices on the same outlet or circuit are also without power.
- Try a different known-good outlet if available.
- If the alarm clears on a different outlet, report the original outlet or circuit issue to the appropriate facilities team.
6. Inspect the Power Cord and Plug
- Inspect the power cord for cuts, crushing, exposed conductors, bent plug blades, burn marks, loose plug fit, or damaged hospital-grade plug.
- Gently manipulate the cord while observing whether the AC power status changes.
- Do not use a cord that is damaged, intermittent, or unable to maintain a secure connection.
- Replace or escalate the cord issue according to facility policy if damage is found.
7. Check for Facility Power or Circuit Issues
- Ask staff whether there was a recent power outage, generator transfer, breaker trip, or OR power issue.
- Check whether the alarm occurred at the same time as other equipment power interruptions.
- Verify whether the issue follows the machine or stays with the room, outlet, or circuit.
- Escalate facility power concerns to facilities, plant operations, or the appropriate electrical support team.
8. Monitor Battery Status
- After AC power is restored, monitor the battery indicator and any related battery alarms.
- Confirm the system is no longer discharging on battery.
- Allow the machine to remain plugged in so the battery can recharge if needed.
- Do not return the machine to patient use if battery or power alarms remain active.
9. Check for Repeat or Intermittent Alarm Behavior
- Leave the unit plugged into a known-good outlet and observe for recurrence.
- Move the cord slightly at the plug and machine connection while watching for AC power dropouts.
- Review whether the alarm returns only with a specific outlet, power cord position, or room location.
- If the alarm repeats under known-good power conditions, treat the issue as a possible device-level power fault.
10. Stop When Resolved
- If plugging the unit into a known working outlet restores AC mains power and the alarm clears, no further service action may be required.
- Confirm normal AC operation.
- Confirm no active battery alarms remain.
- Return the device to service only if it passes normal operational checks and facility policy requirements.
If the Problem Persists
If ACMains POWER FAIL remains active after confirming a known-good outlet, secure power cord connection, acceptable cord condition, and no facility power issue, external and common causes have been ruled out.
Persistent AC mains power failure under known-good power conditions may indicate a device power entry issue, power detection problem, internal power supply path issue, or related internal connection fault.
- Remove the anesthesia machine from service.
- Label it Out of Service.
- Send it for repair or bench evaluation.
- Do not continue clinical use if the machine cannot reliably detect or operate from AC mains power.
Clinical Use Tip
Never troubleshoot this alarm on an active patient in a way that risks interruption of ventilation, monitoring, or anesthesia delivery. If the unit remains on battery or battery time is decreasing, move the patient to a backup device or alternate anesthesia setup first, following clinical direction and facility policy.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"GE Aisys anesthesia machine displayed ACMains POWER FAIL alarm with message Plug in power cable. On battery. Staff reported unit was operating on battery power."
Cause
What was observed during troubleshooting.
Example:
"AC mains power was not detected by the machine. Power cord was loose at the outlet and the unit was operating from battery backup."
Resolution
What action was taken.
Example:
"Verified alarm condition, reseated power cord, tested known-good AC outlet, restored AC mains power, monitored battery status, and confirmed alarm cleared. Unit passed operational checks and was returned to service."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
ACMains POWER FAIL usually means the Aisys correctly detected loss of AC mains power and switched to battery backup. Clinical Engineering should confirm patient safety, restore or verify AC power, check simple external causes first, and escalate only when the machine fails to recognize known-good power.
Clear CCR documentation helps show whether the event was a resolved power-source issue or a device-level fault requiring repair.
That is successful troubleshooting.