FANUC SP9030 Alarm 30: Input Circuit Overcurrent Troubleshooting

FANUC SP9030 means that the spindle system received an input-circuit overcurrent alarm from the common power supply or converter section. The CNC typically displays SP9030 / SSPA:30 OVERCURRENT INPUT CIRCUIT, the spindle amplifier reports 30, and the separate FANUC Power Supply (PS or PSM) normally displays 1.

This is primarily a common-power-supply input fault, not a spindle motor overload alarm. FANUC identifies an unbalanced input supply and an incorrectly selected Power Supply whose maximum output specification is exceeded as principal diagnostic directions. The applicable amplifier maintenance manual adds power-unit-specific checks, including the input specification, AC reactor compatibility and converter hardware.

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

What Does FANUC SP9030 Mean?

FANUC Series 0i-D Maintenance Manual B-64305EN/03 describes SP9030 as overcurrent detected in the Power Supply main-circuit input. It also associates the CNC alarm with Power Supply alarm indication 1 and lists:

• Unbalanced input power

• Incorrect Power Supply selection because the maximum PS output specification is exceeded

FANUC Servo Amplifier αi Series Maintenance Manual B-65285EN/04 identifies the corresponding condition as overcurrent in the converter input circuit. In an αi system, the common power supply converts the incoming three-phase AC supply into the DC link shared by the connected servo and spindle amplifiers. The spindle amplifier can therefore report alarm 30 even though the abnormality is upstream in the Power Supply.

Do not interpret SP9030 as proof that the spindle motor is overloaded or that the spindle amplifier inverter has short-circuited. Confirm the alarm displays on every module before selecting the component to test or replace.

The Meaning of Power Supply Alarm 1 Depends on the Unit

The exact interpretation of alarm 1 is not identical across every FANUC power-unit size and architecture.

For the αi Power Supply models covered by B-65285EN/04:

• On αiPS-5.5 to -15 and 11HV to 18HV, alarm 1 means that the main-circuit power module, or IPM, detected an abnormal condition. FANUC lists an IPM control-supply voltage decrease, input-supply voltage imbalance, an AC reactor that does not match the PSM and IPM failure.

• On αiPS15 to -55 and 30HV to 100HV, alarm 1 means that overcurrent flowed into the main-circuit input. FANUC lists input-supply voltage imbalance, an AC reactor that does not match the PSM and a defective IGBT.

For a βiSVSP with an integrated common power supply, B-65325EN/02 describes SP9030 as an IPM abnormal condition and directs the technician to check input-supply balance and AC reactor compatibility before evaluating the βiSVSP hardware.

These differences matter. A troubleshooting procedure should be selected from the manual for the complete Power Supply or βiSVSP model, including every suffix. Do not assume that every unit with alarm 1 contains the same replaceable subassembly.

Main Causes of FANUC Alarm 30

The verified diagnostic directions for SP9030 include:

• Input-supply voltage imbalance. The incoming phases do not satisfy the power-unit input specification.

• Incorrect Power Supply capacity or selection. The connected servo and spindle system exceeds the maximum output specification of the selected common power supply.

• Incorrect AC reactor specification. The reactor does not match the installed PSM, αiPS or βiSVSP.

• Power-module control-supply abnormality. This applies to the smaller αiPS ranges and βiSVSP configurations identified in the corresponding maintenance manuals.

• IPM, IGBT or power-unit hardware failure. Hardware evaluation is required after the input supply, capacity and reactor specification have been verified.

• Control-board seating or internal connector contact. This is a conditional check when the Power Supply does not show alarm 1, only the spindle side reports 30, or the fault appeared after control-board work. It is not the universal first cause of a confirmed PS alarm 1.

SP9030 is not normally corrected by changing spindle motor parameters, reducing cutting load or replacing an encoder. Those actions belong to other spindle-alarm procedures unless another alarm or test result independently points to them.

1. Confirm SP9030 on Every Module

Before disconnecting any hardware, record all displays:

• The complete CNC message, including SP9030 or SSPA:30

• The number displayed on the spindle amplifier

• The number displayed on the separate Power Supply or PSM

• Any simultaneous servo alarms, especially a converter input-circuit alarm

• Whether the alarm occurs at power-on, when the magnetic contactor turns on, during acceleration or only under a particular operating condition

Also record the complete CNC, Power Supply, spindle amplifier and servo amplifier model numbers, including suffixes. Note the AC reactor model, incoming-voltage class, connected motor/amplifier configuration and any recent replacement, rewiring or control-board work.

If the spindle amplifier shows 30 and the Power Supply shows 1, diagnose the common Power Supply alarm first. On a βiSVSP or another integrated architecture, identify the common-power-supply section of that unit using the applicable manual.

If the Power Supply does not show 1, do not immediately assume that the main power module has failed. Confirm the display history and inspect the communication and board-installation condition specified for the actual unit.

2. Check the Input Power Supply for Imbalance

FANUC's first external electrical direction is to check the input power specification. A qualified technician should compare the incoming three-phase voltage with the specification for the exact Power Supply and machine.

Check:

• All phase-to-phase input voltages, not only one pair

• Whether the imbalance appears at idle or when the main circuit is energized

• Input terminals, circuit protection, fuses and magnetic-contactor connections for a condition that could affect one phase

• Whether the machine's configured voltage class agrees with the installed Power Supply and transformer arrangement

• Whether the same supply abnormality affects other equipment or only this machine

Use properly rated measuring equipment and follow the machine builder's electrical-safety procedure. SP9030 concerns hazardous main-circuit power; live measurements must be performed only by qualified personnel.

Do not automatically apply the AC253 V, AC530 V or 7% voltage-variation values used in other FANUC DC-link overvoltage and source-impedance procedures. The correct limits for SP9030 must come from the input specification of the installed Power Supply and machine.

3. Verify the Common Power Supply Capacity

B-64305EN/03 lists Power Supply selection error as a cause when the maximum PS output specification is exceeded. This check is especially important after:

• A spindle or servo amplifier was added or replaced

• A motor or amplifier capacity was changed

• The original common Power Supply was replaced with a different model

• The machine configuration or simultaneous-axis duty changed

• The alarm began during commissioning or retrofit work

Verify the installed Power Supply against the complete connected servo and spindle system using the applicable FANUC selection documentation and the machine builder's design data. Capacity cannot be confirmed reliably from physical size or a base model number alone.

If the installed PS is undersized or otherwise incompatible, replace it with the correctly specified unit only after the system calculation and compatibility have been confirmed. Do not fit a larger Power Supply as a trial-and-error repair.

4. Check the AC Reactor Specification

B-65285EN/04 and B-65325EN/02 both identify a mismatch between the AC reactor and the installed power unit as a cause of alarm 1 / SP9030.

Confirm:

• The exact Power Supply or βiSVSP model and suffix

• The AC reactor model and rating

• The wiring and terminal arrangement shown in the applicable connection manual

• Whether either component was replaced before the alarm began

• Whether the installed combination agrees with the original machine specification

An electrically connected reactor is not necessarily the correct reactor. Its specification must match the power unit. If the mismatch followed a replacement or retrofit, restore the approved combination before judging the converter hardware.

5. Inspect Control-Board Seating Only When Applicable

Beijing FANUC troubleshooting guidance includes checking whether the amplifier control board or faceplate is loose and reinstalling it correctly. This check should be applied carefully.

It is most relevant when:

• The Power Supply does not retain alarm indication 1 while only the spindle amplifier reports 30

• The alarm began immediately after a control board was removed or replaced

• The front control board or faceplate is visibly not fully seated

• The applicable model manual directs the technician to inspect the connection between the control and power printed-circuit boards

Isolate the machine power and wait for the specified DC-link discharge period before touching the amplifier. Use ESD protection, inspect connector alignment and insert the board fully according to the exact replacement procedure.

Do not repeatedly remove and insert an undisturbed board as a substitute for checking a confirmed Power Supply alarm 1. On a split αi system, make sure the board being inspected belongs to the module indicated by the displays. On an integrated βiSVSP, follow the unit-specific procedure.

6. Evaluate the Power Hardware

If input balance, Power Supply capacity, AC reactor specification, wiring and any applicable board-seating condition are correct, the remaining official directions are hardware-related.

Depending on the exact unit, FANUC may identify:

• Power-unit replacement for an IPM control-supply abnormality

• IPM failure

• IGBT failure

• Replacement of the βiSVSP in an integrated system

Component-level replacement must follow the applicable FANUC procedure. Some power modules are serviced at unit level, and the available replaceable assembly differs by series. Do not order an IPM, IGBT, control board, PSM or complete amplifier solely from the CNC alarm number.

If a replacement unit is required, browse FANUC servo, spindle and power drives or send REACO CNC the complete model and suffix for a compatibility check.

When Should the Power Supply or Amplifier Be Replaced?

Replacement belongs at the end of the external checks, except when the exact manual identifies an immediate internal power-module abnormality and the required supply checks have already been completed.

Before replacement, verify:

• The CNC, spindle-amplifier and Power Supply alarm displays agree

• Incoming power satisfies the installed unit's specification and is not unbalanced

• The common Power Supply capacity matches all connected amplifiers and motors

• The AC reactor is the correct specification

• The relevant power and control connections are correct

• Any recent board or unit replacement has been checked for correct installation and compatibility

• The complete replacement number, suffix, voltage class and architecture have been confirmed

For a split αi system with PS alarm 1, replacing only the spindle amplifier may leave the actual common-power-supply fault unchanged. For an integrated βiSVSP, the common power supply and spindle functions may be contained in the same physical unit, so the applicable replacement direction is different.

Difference Between SP9030, SP9012, SP9022 and SP9029

These alarms all involve current or load, but they identify different locations and detection conditions. Always use the complete display combination instead of treating every “overcurrent” message as a spindle-amplifier failure.

FANUC SP9030 Diagnostic Table

Recommended Troubleshooting Order

1. Confirm SP9030 on the CNC, 30 on the spindle amplifier and whether the Power Supply displays 1.

2. Record all complete module models and suffixes, the AC reactor model, voltage class and alarm timing.

3. Identify whether the machine uses a separate αi Power Supply or an integrated βiSVSP/common-power-supply architecture.

4. Check all incoming phases against the exact input-power specification and investigate any imbalance.

5. Verify that the Power Supply selection and maximum output capacity match the connected servo and spindle system.

6. Confirm that the AC reactor specification matches the installed Power Supply or βiSVSP.

7. If only the spindle side reports 30 or the alarm followed board work, inspect the applicable control-board seating and internal connectors with power isolated.

8. After the external checks are correct, test the IPM, IGBT or complete power unit according to the model-specific maintenance manual.

9. Repair or replace the exact confirmed faulty assembly; do not automatically replace only the spindle amplifier in a split system.

10. Retest without a workpiece using the machine builder's approved procedure and diagnose any new 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, Power Supply alarm code 1 and SP9030 alarm mapping

• FANUC Series 0i-D/0i Mate-D Maintenance Manual, B-64305EN/03, SP9030 alarm list

• FANUC AC Servo Motor βi-B/βi Series, AC Spindle Motor βi Series, Servo Amplifier βi-B Series Maintenance Manual, B-65325EN/02, βiSVSP SP9030 procedure

• Applicable FANUC Servo Amplifier Descriptions and connection manual for Power Supply and AC reactor selection

• Beijing FANUC SP9030 technical guidance, input-circuit overcurrent troubleshooting

Always use the manual edition, input specification and machine electrical documentation that apply to the exact CNC, Power Supply, AC reactor, spindle amplifier, servo amplifiers, motors and machine configuration.

Need Help With FANUC SP9030 Alarm?

REACO CNC provides independent FANUC Power Supply and spindle-amplifier testing, repair, compatibility checking and replacement support. Send us the CNC alarm screen, spindle-amplifier display, Power Supply display, complete CNC and amplifier models with suffixes, AC reactor model, incoming-voltage measurements, alarm timing and details of recent replacement or wiring work.

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 input-power, capacity, reactor, board and hardware procedure depends on the exact Power Supply architecture and machine configuration.