FANUC SP9022 Alarm 22: Spindle Amplifier Overload Current Troubleshooting

FANUC SP9022 means that current exceeding the spindle amplifier's time rating continued to flow. The CNC displays SP9022 or a series-dependent serial spindle alarm, while the spindle amplifier displays alarm 22.

FANUC identifies frequent acceleration and deceleration and a high cutting load as typical causes. The correct first response is to reduce the operating load and verify the spindle motor parameters. For a dual-winding motor, the applicable motor parameters and the winding-switching section of the PMC ladder must also be checked.

For the surrounding spindle alarm numbers, see the FANUC Serial Spindle Alarm Codes SP9001–SP9033.

What Does FANUC SP9022 Mean?

A spindle amplifier can provide current above its continuous rating for a limited time during acceleration or cutting. SP9022 is issued when the current exceeds the amplifier's permitted time rating. FANUC B-65285EN/04 describes the condition as overcurrent exceeding the time rating of the spindle amplifier.

This wording is important. Alarm 22 does not necessarily mean that an instantaneous short circuit occurred. It indicates that the current level and its duration exceeded the amplifier's permitted overload capability.

Common operating clues include:

• The alarm occurs after repeated spindle acceleration and deceleration.

• The alarm occurs only during heavy cutting.

• A new program or cycle increases the spindle duty cycle.

• The alarm begins after spindle motor parameters are initialized, restored or changed.

• On a dual-winding motor, the alarm appears during or after a winding-range transition.

Record the exact condition instead of testing by repeatedly resetting the alarm.

Main Causes of FANUC Alarm 22

The verified diagnostic directions are:

• Acceleration/deceleration frequency is too high. Repeated speed changes can keep the current above the short-time rating for too long.

• Cutting load is too high. Excessive depth of cut, feed, tool load or mechanical resistance may increase spindle current.

• Motor-specific spindle parameters are incorrect. Incorrect initialized data can cause unsuitable current control for the installed motor.

• Dual-winding motor settings are incorrect. This applies only to a spindle using a supported dual-winding motor.

• The winding-switching ladder sequence is incorrect. This applies only when the alarm is associated with winding switching.

• The spindle amplifier is abnormal. Consider this after the operating conditions, motor data and applicable switching configuration have been verified.

Do not assume every machine uses dual-winding control. Confirm the complete motor model, amplifier model and machine configuration first.

1. Confirm SP9022 and Amplifier Alarm 22

Before changing parameters or replacing hardware, confirm:

• The CNC shows SP9022, SP AMP OVER CURRENT, SERIAL SPINDLE ALARM, or the applicable series-specific message.

• The spindle amplifier status display shows 22.

• Whether the alarm occurs during acceleration, deceleration, constant-speed running, cutting or winding switching.

• The spindle load indication immediately before the alarm.

• Whether spindle parameters, the motor, amplifier or PMC ladder were recently changed.

Record the complete CNC model, spindle amplifier model and suffix, spindle motor model, software information and machine operating condition. The CNC-side number can vary by series, so the amplifier display and the exact FANUC manual remain important.

2. Reduce Acceleration, Deceleration and Cutting Load

FANUC's primary alarm 22 action is to ease the operating conditions.

If SP9022 occurs during repeated speed changes:

• Reduce the frequency of spindle acceleration and deceleration.

• Review whether the cycle commands unnecessary stops or speed reversals.

• Increase acceleration or deceleration time only through the approved machine-builder or FANUC procedure.

• Confirm that the spindle duty cycle is within the motor and amplifier specification.

If the alarm occurs during cutting:

• Observe the spindle load under the failing condition.

• Reduce the cut, feed or other machining demand to determine whether the alarm is load-dependent.

• Check for abnormal mechanical resistance, a damaged tool or another condition that increases cutting load.

• Compare the failing cycle with a known normal operating condition.

The goal is not merely to suppress the alarm. The revised operating condition must remain within the machine, spindle motor and amplifier ratings while still meeting the machine builder's requirements.

3. Verify the Spindle Motor Parameters

FANUC CNC alarm tables instruct technicians to check and correct the parameters for SP9022. Beijing FANUC guidance specifically calls for confirmation of the spindle initialization parameters.

Before changing any data:

1. Back up the current CNC and spindle parameters.

2. Record the exact spindle motor model, including all suffixes and specification codes.

3. Compare the motor-specific parameters with the applicable FANUC AC Spindle Motor Parameter Manual B-65280 series and the machine builder's original data.

4. Check whether the alarm began after parameter initialization, restoration, CNC replacement or amplifier replacement.

5. If parameter reinitialization is required, use the exact motor data and the procedure for the installed CNC and spindle system.

Do not initialize the spindle from an approximate motor model or copy values from a visually similar machine. Incorrect motor data can change current control, acceleration performance and protection behavior.

4. Check Dual-Winding Motor Parameters and Ladder Logic

This step applies only when the machine uses a dual-winding spindle motor.

If alarm 22 occurs during a winding-range change, verify:

• The motor is correctly identified as the installed dual-winding specification.

• The dual-winding motor parameters match the exact motor and amplifier configuration.

• The winding-switching control section of the PMC ladder matches the machine builder's sequence.

• The alarm timing corresponds to the winding-switching command rather than normal cutting or repeated acceleration.

Do not modify the PMC ladder simply to bypass the alarm or switching confirmation. Winding switching changes the motor power-circuit configuration and must follow the approved FANUC and machine-builder design.

If the spindle amplifier displays 15 instead of 22, follow the FANUC SP9015 spindle and output switching alarm guide rather than diagnosing SP9022.

5. Determine Whether the Spindle Amplifier Is Faulty

If the load is within specification, acceleration and deceleration are reasonable, the motor parameters are correct, and the applicable dual-winding configuration is verified, the spindle amplifier may be abnormal.

Before replacement, confirm:

• The complete FANUC amplifier part number and every suffix

• Compatibility with the installed CNC, motor and spindle software

• The amplifier's current capacity and supported motor configuration

• That the same alarm occurs under a controlled, documented test condition

Beijing FANUC's extended troubleshooting guidance includes spindle amplifier replacement after the preceding checks. FANUC B-65285EN/04, however, emphasizes easing the operating conditions for alarm 22. Therefore, replacement should be an end-stage decision supported by testing, not the automatic first action.

If a replacement is required, browse FANUC servo, spindle and power drives or send REACO CNC the complete amplifier and motor models for a compatibility check.

Difference Between SP9012 and SP9022

Both alarms involve current, but they describe different protection conditions:

For an actual alarm 12, see the FANUC SP9012 DC Link Overcurrent troubleshooting guide.

FANUC SP9022 Diagnostic Table

Recommended Troubleshooting Order

1. Confirm SP9022 on the CNC and alarm 22 on the spindle amplifier.

2. Record whether it occurs during acceleration, deceleration, cutting or winding switching.

3. Observe the spindle load and compare the failing condition with normal operation.

4. Reduce excessive acceleration/deceleration frequency and cutting load.

5. Back up and verify the spindle motor-specific parameters using the exact motor model.

6. For a dual-winding motor only, check the motor parameters and winding-switching ladder section.

7. Retest under a controlled operating condition.

8. If the alarm remains with normal load and verified settings, test or replace the exact compatible spindle amplifier.

9. If another alarm appears, diagnose that alarm separately.

Technical References

• FANUC AC Servo Motor αis/αi Series, AC Spindle Motor αi Series, Servo Amplifier αi Series Maintenance Manual, B-65285EN/04, Alarm Code 22

• FANUC Series 0i-D/0i Mate-D Maintenance Manual, B-64305EN/03, SP9022 alarm list

• FANUC AC Spindle Motor αi/βi Series Parameter Manual, B-65280 series, motor-specific parameters and initialization

• Beijing FANUC SP9022 technical guidance, spindle amplifier overload current troubleshooting

Always use the manual edition that applies to the exact CNC, spindle amplifier, spindle motor, software and machine configuration.

Need Help With FANUC SP9022 Alarm?

REACO CNC provides independent FANUC spindle alarm analysis, amplifier testing, repair and replacement support. Send us the CNC alarm screen, amplifier display, complete CNC model, exact spindle amplifier and motor models, spindle load information, alarm timing and details of recent parameter or ladder changes.

Visit the FANUC Technical Support Center for more FANUC alarm guides, or contact REACO CNC for assistance.

Reference Source: Beijing FANUC. This article is based on FANUC technical documentation. The applicable parameter, switching and replacement procedure depends on the exact CNC, spindle amplifier, motor and machine configuration.