A81L-0001-0158 Fanuc AC Servo Motor Reactor A81L00010158 A8IL-OOOI-OI58

Fanuc A81L-0001-0158 | 3-Phase Line Reactor — 125A, 0.045mH, Compatible with αiPS 30 Power Supply Module

Part Number: A81L-0001-0158

Type: AC Line Reactor (3-Phase)

Current Rating: 125 A

Inductance: 0.045 mH

Phase: 3-Phase

Series: A81L-0001 (Fanuc / Pertoronics Reactor Series)

Compatible Power Supply: A06B-6140-H030 (αi PS 30) / A06B-6110-H030

Condition: New / Refurbished / Surplus 

Overview

The Fanuc A81L-0001-0158 is a three-phase line reactor rated at 125A and 0.045mH, designed for installation on the AC input side of Fanuc Alpha i series power supply modules. It is specified as the companion reactor for the A06B-6140-H030 (αi PS 30, 30kW) and the A06B-6110-H030 power supply modules — the high-capacity end of the Fanuc Alpha i PSM range used in large CNC machining centres, turning centres, and multi-axis systems with combined servo and spindle power demands up to 30kW.

A line reactor is a three-phase inductive impedance component inserted between the facility's AC supply mains and the power supply module's input terminals. It is not a transformer and does not change voltage levels.

Its function is electrical: the inductive impedance it presents limits the rate of change of input current (dI/dt) during the rectifier's commutation switching and during mains voltage transients, controlling the current waveform that the power supply's input rectifier draws from the supply.

This has direct consequences for both the power supply's own reliability and the quality of the electrical supply feeding it — two concerns that become increasingly significant as drive system power levels increase.

At 125A rated current, the A81L-0001-0158 is sized for the full input current demand of the αi PS 30 operating at rated 30kW output with a typical three-phase 200–240V supply. The 0.045mH inductance provides the impedance characteristic that Fanuc specifies for this power supply class — sufficient to limit harmonic current injection and dI/dt stress without introducing a voltage drop that meaningfully reduces the DC bus voltage under normal operating conditions.

Key Specifications

Why a Line Reactor Is Required — The Engineering Case

The rectifier bridge at the front end of a PWM drive's power supply draws current from the AC mains in short, high-magnitude pulses rather than as a smooth sinusoidal waveform. Each time the DC bus capacitors demand replenishment — which happens at each peak of the rectified AC waveform — the rectifier draws a burst of current with very fast rise and fall times. Without any limiting impedance, these current pulses can be extremely high, generating two distinct categories of problem.

The first is harmonic current injection into the facility's AC supply.

The non-sinusoidal current drawn by the rectifier contains harmonic components at multiples of the supply frequency.

These harmonics circulate through the supply impedance, creating harmonic voltage distortion at the common coupling point — distortion that can interfere with other equipment sharing the same supply bus, cause unexplained tripping of other drives and sensitive equipment, and in extreme cases create resonance effects in power factor correction capacitor banks.

Most industrial electrical standards and grid codes impose limits on harmonic current injection, and line reactors are the standard compliance means for drive inputs.

The second is stress on the rectifier diodes and the input capacitors of the power supply itself.

High dI/dt commutation pulses create voltage spikes across parasitic inductance in the wiring, and the repetitive peak current demands accelerate capacitor wear.

The A81L-0001-0158's 0.045mH inductance slows the current rise rate, reducing peak commutation current and the associated voltage stresses within the PSM.

αi PS 30 / A06B-6140-H030 — Power Supply Context

The A06B-6140-H030 is the 30kW unit in Fanuc's Alpha i PSM (Power Supply Module) range. Within the Alpha i drive system, the PSM provides the regenerative DC bus that feeds all servo and spindle amplifier modules in the cabinet.

At 30kW, this module serves the larger Fanuc CNC configurations: multi-axis machining centres with high-power spindles, turning and milling centres with multiple feed axes, and any system where the combined servo and spindle demand reaches the 30kW class.

The A81L-0001-0158 sits between the facility's AC supply and the A06B-6140-H030's L1/L2/L3 input terminals. Fanuc requires a line reactor on all Alpha i PSM installations — the reactor is not an optional add-on but a specified installation component.

Operating the PSM without the reactor risks exceeding the rectifier's peak current rating during mains disturbances, increases harmonic distortion at the supply point, and can reduce the service life of the PSM's input capacitors through elevated ripple current stress.

The A06B-6110-H030 — the earlier Alpha (non-i) generation equivalent at the same 30kW class — shares the same reactor specification, which is why the A81L-0001-0158 appears as the compatible reactor for both generations.

A81L-0001 Reactor Series — Pertoronics Manufacture

The A81L-0001 series covers Fanuc's complete range of line reactors, each matched by inductance and current rating to a specific PSM or drive module. The reactors in this series are manufactured by Pertoronics, a specialist magnetics manufacturer whose products Fanuc has specified across its drive system range.

Within the series, different suffix numbers identify different current and inductance combinations corresponding to different PSM power classes — a smaller reactor serves the αi PS 5.5 and PS 11 modules, while the larger A81L-0001-0158 at 125A serves the PS 30 class.

When sourcing a replacement, matching the full part number A81L-0001-0158 is essential — substituting a reactor from a different suffix that provides different inductance or current rating can result in insufficient harmonic suppression (too low inductance) or excessive voltage drop under load (too high inductance), either of which affects drive system performance and may trigger input supply alarms on the PSM.

Installation Position and Wiring

The A81L-0001-0158 is installed in series with the three-phase AC supply lines feeding the PSM — upstream of the PSM's mains input breaker or contactor, between the distribution panel and the PSM input terminals.

The reactor's three terminals (one per phase) connect in-line: supply side conductors terminate on one set of terminals, PSM input conductors on the other.

Correct phase sequence is not critical for reactor function, but the conductor size to the reactor must be rated for the full 125A continuous current plus any short-term overload the installation may experience.

The reactor's housing should be mounted in the cabinet with adequate clearance around the core for natural air circulation — line reactors operating at 125A generate meaningful heat from core losses and conductor resistance, and restricted airflow causes surface temperature to rise above the rated operating limit.

The reactor must not be enclosed against an adjacent component with no ventilation gap.

FAQ

Q1: Is the A81L-0001-0158 a required component or optional for the A06B-6140-H030?

Fanuc specifies a line reactor as a required installation component for the Alpha i PSM range — it is not optional. Operating the A06B-6140-H030 without the specified reactor risks elevated peak current stress on the PSM's rectifier and input capacitors, increased harmonic distortion on the supply, and potential violation of EMC requirements applicable to the machine installation. The A81L-0001-0158 at 125A / 0.045mH is the reactor Fanuc specifies for this specific PSM model.

Q2: Can a generic third-party line reactor be substituted for the A81L-0001-0158?

In principle, a third-party reactor with the same inductance (0.045mH) and a current rating of at least 125A on a three-phase 200–240V supply can perform the same electrical function. However, the A81L-0001-0158 is a Fanuc-specified part with defined thermal and electrical characteristics matched to the PSM.

Any substitution should confirm that the replacement reactor's continuous current rating, inductance, and insulation class meet or exceed the original specification. Using an undersized reactor — lower current rating or lower inductance — creates the same risks as operating without a reactor.

Q3: What happens if the reactor is installed with incorrect wiring — e.g., wrong phase-to-terminal assignment?

The line reactor's inductance is phase-independent — it presents the same impedance regardless of which supply phase connects to which reactor terminal. Incorrect phase assignment at the reactor does not affect reactor function.

However, if the phase sequence at the PSM input changes as a result of wiring, the PSM may detect a phase sequence error and alarm.

The reactor terminals should be wired in the same phase sequence as the PSM installation requires, with supply phase L1 through to PSM terminal L1 via the corresponding reactor terminal, and so on.

Q4: The reactor is generating heat during operation — is this normal?

Yes. A 125A three-phase line reactor generates heat from two sources: core losses (hysteresis and eddy current losses in the magnetic core) and resistive losses in the copper winding conductors at full load current.

At rated 125A, moderate surface warmth — typically 40°C to 60°C above ambient depending on the specific unit and mounting conditions — is normal and expected. Ensure the reactor has adequate clearance in the cabinet for air circulation.

If the reactor surface is hot to the touch and the installation is within its rated current, restricted ventilation is the most common cause; if the reactor is overheating with adequate ventilation, measure the actual line current to confirm the reactor is not carrying sustained overcurrent above its 125A rating.

Q5: Does the A81L-0001-0158 require any maintenance?

Line reactors have no moving parts and no consumable components in normal operation.

Maintenance is limited to periodic inspection: check that mounting fasteners remain tight (vibration in a machine tool cabinet can loosen over time), inspect the input and output wiring connections for signs of overheating at the terminals (discolouration or hardened insulation indicates a loose connection that has been running warm), and verify there is no physical damage to the reactor body or insulation.

If the reactor is audibly humming beyond a low background level, this can indicate a loose lamination in the core — a condition that does not immediately impair function but warrants investigation and eventual replacement.