Beckhoff AX8000 servo installation fuse selection

Beckhoff AX8000 Multi Axis Servo System Installation and Fuse Protection Selection Guide

In modern high-precision automated production lines, multi axis synchronous motion control imposes strict requirements on the real-time performance, power density, and modular scalability of servo drive systems. The Beckhoff AX8000 multi axis servo system, with its extremely short EtherCAT cycle time (minimum 62.5 μ s, paired with distributed clock), scalable DC bus design, and flexible safety features (TwinSAFE STO/SS1/Safe Motion), has become the core driving platform for high-end mechanical equipment. However, the reliable operation of the system depends not only on selection calculations, but also on standardized mechanical installation, precise DC bus capacitor matching, UL/CE compliant fuse protection selection, and compliance understanding of Dual Use export control clauses. This article will be based on the technical manual of the AX8000 series, and provide an in-depth analysis of the full stack technical points of the system, including hardware architecture, installation specifications, power/ground/fuse protection design, and preventive maintenance.

Chapter 1: Product Architecture and Selection Overview

1.1 Modular hardware system

The AX8000 adopts a modular combination structure, with all modules having a width of 60mm or 90mm and a uniform height of 230mm. It can be quickly connected to the DC bus, 24V control power, and EtherCAT bus through AX Bridge without tools.

Core module type:

Power module (AX86xx): converts single-phase/three-phase AC or DC power into a stable DC bus voltage (up to 848 VDC).

AX8600: DC input (560/640 VDC), 50 A, suitable for pure DC bus power supply scenarios.

AX8620: Single phase 100-240 VAC or three-phase 200-480 VAC, 20 A, built-in C3 class filter.

AX8640: Three phase 200-480 VAC, 40 A, suitable for high-power drive groups.

Axis module (AX81x8 single axis/AX8206 dual axis):

AX8108: 8 A/4 A (8/16 kHz switching frequency), narrow module (60mm).

AX8118：18 A / 9 A， Wide module (90mm).

AX8128：28 A / 14 A， Wide module (90mm).

AX8206: Dual axis, 6 A per axis, narrow module (60mm), supports two channels to connect motors of different powers.

Combination module (AX85xx): Integrating the power module with the single axis module to save cabinet space.

AX8525:25 A-axis current+50 A DC bus output.

AX8540:40 A-axis current+80 A DC bus output.

Capacitor module (AX8810): expands the DC bus capacitor (1755 μ F), absorbs braking feedback energy, and reduces braking resistance losses.

1.2 TwinSAFE Safety Function Selection

The AX8000 axis module is divided into three sub models according to safety level (distinguished by the b-digit in the model):

B=0: No security function.

B=1: Integrated TwinSAFE STO (Safe Torque Off) and SS1 (Safe Stop 1), triggered through FSoE protocol or hard wired safety input, compliant with SIL 3/PL e.

B=2: Integrated TwinSAFE Safe Motion, supporting up to 17 safety functions (including SLS, SOS, SS2, SLP, SBC, SBT, etc.).

Important constraint: Safety functions require the use of Beckhoff certified motor feedback systems (such as EnDat 3 encoders with SIL2 or SIL3 capabilities for OCT). If a third-party motor is equipped with a safety encoder, the equipment manufacturer must complete FMEDA analysis and EMC testing on their own.

Chapter 2: Mechanical Installation Specifications and Ventilation Requirements

2.1 Installation location and heat dissipation space

The AX8000 must be installed vertically inside the control cabinet, with a ventilation space of no less than 50mm reserved above and below to ensure the forced convection heat dissipation effect of the built-in temperature control fan. The installation base plate should be a conductive and galvanized metal plate to achieve low impedance grounding.

Standard installation process:

Prefabricate M5 threaded holes on the installation plate according to the Beckhoff universal drilling template.

Place the power module on the leftmost side and secure it with M5 × 5 screws (strength grade 8.8) with a torque of 6 Nm.

Arrange the axis modules to the right in sequence, and it is recommended to arrange them from high to low power (such as AX8640 → AX8118 → AX8206 → AX8108) to optimize the DC bus current distribution.

Insert the grounding Hanger onto the grounding bolt of the right module, and then tighten it onto the left grounding bolt of the adjacent module to form a continuous low impedance grounding chain.

2.2 Stacking and Storage Restrictions

Under the original packaging, the stacking height of power/shaft/capacitor modules shall not exceed 8 layers, and the combination module (AX85xx) shall not exceed 3 layers. Long term storage (>5 years) requires the execution of a capacitance forming procedure - power on and no-load operation for 60 minutes to restore the dielectric performance of the DC bus capacitor.

Chapter 3: Electrical Installation and Grounding/EMC Core Points

3.1 Power wiring and fuse protection

The power wiring of AX8000 varies depending on the module type, and it is necessary to strictly distinguish between single-phase/three-phase and DC input:

Key points for module input terminal wiring