SIEMENS C98043-A7004-L2 Replacement for SIMOREG 6RA70

Product Overview

SIEMENS C98043-A7004-L2 Replacement for SIMOREG 6RA70: Seamless Transition & Compatible Upgrade

The SIEMENS C98043-A7004-L2 is a field excitation printed circuit board (PCB) designed for the SIMOREG 6RA70 series DC drive systems. As aging SIMOREG 6RA70 installations reach end-of-service life and original boards become increasingly difficult to source, plant engineers and procurement teams face mounting pressure to locate verified replacement units that maintain full electrical and functional compatibility with existing drive cabinets. TOPNLMS stocks the C98043-A7004-L2 as a direct drop-in replacement, enabling facilities to restore drive operation with minimal downtime and without requiring redesign of the surrounding control architecture.

The SIMOREG 6RA70 platform has been widely deployed in steel mills, paper machines, extruder lines, crane drives, and winding applications across Europe and Asia. Many of these installations remain in productive service, supported by a combination of preventive maintenance and targeted board-level replacements. The C98043-A7004-L2 field excitation board governs the DC field current regulation circuit, interfacing directly with the armature control board and the firing pulse board within the 6RA70 drive stack. When this board fails — typically presenting as loss of field current, erratic speed regulation, or drive fault codes F023 or F024 — the entire drive becomes inoperable until the board is replaced or repaired.

For sites running multiple 6RA70 converters, the C98043-A7004-L2 is a critical spare. It is physically compatible with the standard 6RA70 drive chassis and mounts using the original PCB standoffs and connector harness. No rewiring of the field circuit terminals is required. The board communicates with the main control electronics via the internal bus structure of the 6RA70 rack, and parameter settings stored in the CUD1 central unit board (such as P100 field current setpoint and P101 field weakening threshold) are preserved during board swap, provided the CUD1 itself remains intact.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful 6RA70 field excitation board replacement rarely occurs in isolation. In most retrofit and modernization projects, the C98043-A7004-L2 is sourced alongside a broader set of drive components to ensure the entire system is restored to reliable operating condition. The CUD1 central unit board — the main intelligence of the 6RA70 drive — is frequently evaluated at the same time, as it shares the internal bus with the field excitation board and may carry accumulated faults or degraded firmware. Similarly, the firing pulse board within the 6RA70 stack is a common co-replacement item, particularly in drives that have experienced thyristor misfiring events that may have stressed the field circuit.

In cabinet-level retrofits, the 6RA70 drive is often mounted alongside a SIMOREG 6RA24 or earlier 6RA26 series converter that is being phased out. Engineers migrating from these older platforms to the 6RA70 architecture will find that the field excitation board replacement is one of the final steps in commissioning the upgraded drive stack. The SINAMICS DCM DC converter, Siemens’ current-generation replacement for the SIMOREG family, is increasingly specified for new installations, but the 6RA70 remains the dominant platform in brownfield sites where full drive replacement is not yet justified.

On the communications side, many 6RA70 installations use the CBP2 PROFIBUS communication board or the CBD CAN bus board to integrate the drive into a plant-wide control network. These communication boards are mounted in the option slots of the 6RA70 chassis and are unaffected by field excitation board replacement, but they are commonly inspected and tested during the same maintenance window. For sites using PROFIBUS DP to connect the 6RA70 to a SIMATIC S7-300 or S7-400 PLC, the drive’s node address and baud rate settings stored in the CBP2 board remain intact during a C98043-A7004-L2 swap.

Power supply integrity is another consideration during field board replacement. The SITOP PSU power supply units feeding the 6RA70 control electronics should be verified for correct output voltage before the replacement board is energized. A degraded 24 VDC supply is a known cause of premature PCB failure in the SIMOREG series. Additionally, the signal isolators and terminal modules used in the field current feedback circuit — including the LEM current transducer mounted on the field output terminals — should be inspected for drift or damage as part of the same service event.

For facilities managing a larger installed base of SIMOREG drives, TOPNLMS can support bulk procurement of the C98043-A7004-L2 alongside related boards such as the C98043-A7001 armature control board and the C98043-A7002 firing pulse board, enabling a complete drive board kit to be held as on-site critical spares inventory.

Retrofit Guidance FAQ

Q: Does replacing the C98043-A7004-L2 require any rewiring of the field circuit?
A: No. The replacement board uses the identical connector harness and PCB footprint as the original. Field terminal wiring at the drive’s F1/F2 output terminals remains unchanged. The board swap is a direct plug-in replacement within the 6RA70 chassis.

Q: Will my existing drive parameters be lost during the board swap?
A: Parameters are stored on the CUD1 central unit board, not on the C98043-A7004-L2 field excitation board. Provided the CUD1 is not replaced simultaneously, all parameter sets — including field current setpoints, field weakening curves, and speed controller gains — are retained without re-entry.

Q: Is the C98043-A7004-L2 compatible with all frame sizes of the SIMOREG 6RA70?
A: The C98043-A7004-L2 is designed for the SIMOREG 6RA70 series. Compatibility across specific frame sizes (e.g., 6RA7013 through 6RA7095) should be verified against the drive’s hardware configuration. TOPNLMS technical support can assist with frame-size-specific confirmation prior to order.

Q: What fault codes typically indicate a failed field excitation board?
A: Common fault indications include F023 (field current too low), F024 (field current too high), and A078 (field current controller alarm). These faults, particularly when they persist after parameter checks, often point to a failed or degraded C98043-A7004-L2 board.

Q: Can this board be used in a SIMOREG 6RA24 or 6RA26 drive?
A: No. The C98043-A7004-L2 is specific to the SIMOREG 6RA70 architecture. The earlier 6RA24 and 6RA26 series use a different board set and are not electrically or mechanically compatible with 6RA70 PCBs.

Q: What is the lead time and shipping arrangement?
A: Units are stocked in Xiamen, China and are available for same-day or next-business-day dispatch. International shipping is available via DHL Express, FedEx, and UPS. Estimated transit time to Europe is 3–5 business days; to Southeast Asia, 2–3 business days.

Warranty Assurance

Every C98043-A7004-L2 unit supplied by TOPNLMS is covered by a 12-Month Warranty from the date of shipment. Prior to dispatch, each board undergoes a pre-shipment functional inspection to verify connector integrity, component condition, and absence of physical damage. Units that do not pass inspection are not shipped.

In the event of a warranty claim, TOPNLMS provides a replacement unit or full refund, subject to return of the defective board for evaluation. Our after-sales response target is within 24 hours of claim submission. Warranty coverage applies to manufacturing defects and component failure under normal operating conditions; it does not cover damage resulting from incorrect installation, overvoltage events, or physical mishandling.

For procurement teams requiring documentation, TOPNLMS can provide a certificate of conformity, packing list, and commercial invoice with HS code declaration for customs clearance. Volume orders and blanket purchase agreements are supported for MRO and spare parts programs.