KONGSBERG VT25-373-99/X9 Retrofit-Compatible Power Supply for Legacy Systems

KONGSBERG VT25-373-99/X9 Retrofit-Compatible Power Supply for Legacy Systems

The KONGSBERG VT25-373-99/X9 is a retrofit-compatible industrial power supply unit engineered to support smooth modernization of legacy automation systems. As original KONGSBERG control platforms age beyond their published end-of-life dates, procurement engineers and system integrators face mounting pressure to source verified replacement components that preserve existing wiring infrastructure, backplane architecture, and control logic without triggering a full system overhaul. The VT25-373-99/X9 addresses this challenge directly — delivering a reliable, drop-in compatible power supply solution for KONGSBERG-based control cabinets operating in marine, offshore, and industrial automation environments.

KONGSBERG automation systems have long been deployed in dynamic positioning (DP) systems, process control platforms, and integrated automation systems (IAS) aboard vessels and in onshore industrial facilities. When the original power supply unit in a VT25-series rack begins to show signs of degradation — output voltage instability, thermal shutdown events, or capacitor aging — the operational risk to the entire control loop escalates rapidly. Replacing the VT25-373-99/X9 with a verified spare restores system stability without requiring reprogramming of the controller, reconfiguration of I/O modules, or modification of HMI display pages.

Upgrade Compatibility Table

Retrofit Planning for Existing Automation Systems

Successful retrofit of the VT25-373-99/X9 begins well before the unit arrives on site. Engineers should audit the full VT25 rack assembly to identify co-installed modules that share the same power rail — including analog I/O modules, digital output modules, and any serial communication modules connected to the backplane. In many legacy KONGSBERG IAS installations, the VT25 rack also hosts a CPU or controller module that manages process variable acquisition and alarm handling; confirming that the replacement power supply meets the aggregate current draw of all installed modules is a non-negotiable pre-installation step.

For systems where the VT25 rack interfaces with a KONGSBERG operator station or HMI panel via a proprietary serial link or Ethernet-based supervisory network, the power supply replacement itself does not affect the communication layer — but a controlled power cycle will temporarily interrupt the data link. Operators should coordinate with the control room to suppress nuisance alarms and place the affected loop in manual mode before initiating the swap. If the rack also contains a KONGSBERG network interface module or gateway card bridging legacy serial protocols to a modern DCS backbone, that module’s configuration is stored in non-volatile memory and will be retained through the power cycle.

In control cabinet upgrades where the VT25 rack is being partially modernized — for example, replacing aging analog I/O cards with updated signal conditioning modules while retaining the existing backplane and rack chassis — the VT25-373-99/X9 power supply serves as the stable foundation that makes incremental migration feasible. Rather than replacing the entire rack assembly, engineers can extend the operational life of the existing infrastructure by sourcing verified spare power supplies, allowing the modernization budget to be directed toward higher-value upgrades such as communication protocol migration from RS-232/RS-485 serial links to Modbus TCP or PROFINET.

Where the retrofit scope extends to adjacent control cabinets, it is common to encounter companion components such as KONGSBERG VT25-series termination panels, signal isolators for 4–20 mA loops, and 24 VDC distribution modules that feed field instruments. Ensuring that the replacement power supply’s output ripple and regulation characteristics are within specification is particularly important in these multi-cabinet architectures, where voltage sag on the power rail can propagate across the backplane and affect the accuracy of analog input modules reading pressure transmitters, flow meters, or temperature sensors.

For installations where a programming cable or laptop-based engineering tool is required to verify module configuration post-replacement, engineers should confirm that the KONGSBERG engineering software version in use is compatible with the firmware revision of the controller module in the rack. In some legacy VT25 installations, the controller module’s firmware predates current software releases, and a firmware update — if required — should be planned as a separate, controlled activity distinct from the power supply replacement itself.

Downtime Control During System Migration

Minimizing unplanned downtime is the primary operational constraint in any power supply replacement on a live automation system. For the VT25-373-99/X9, the recommended approach is a planned maintenance window during which the affected rack is de-energized in a controlled sequence: first placing all controlled outputs in a safe state, then transferring any active control loops to redundant controllers or manual operation, and finally isolating the rack from the AC supply before removing the failed or degraded power supply unit.

Where the VT25 rack supports a redundant power supply configuration, the replacement can often be performed with the rack remaining energized on the secondary supply — significantly reducing the impact on process continuity. Engineers should verify the redundancy architecture of the specific rack assembly before assuming hot-swap capability, as not all VT25 rack configurations support concurrent dual-supply operation.

Original program logic stored in the controller module is not affected by a power supply replacement, provided the controller’s battery-backed RAM or flash memory is intact. Before initiating the replacement, it is good practice to export a backup of the current controller program using the KONGSBERG engineering workstation, ensuring that a verified program image is available for restoration in the unlikely event of a controller fault during the power cycle. HMI display pages, alarm setpoints, and trend configurations stored in the operator station are similarly unaffected by the rack-level power cycle.

Post-installation commissioning should include a systematic check of all I/O module status indicators, verification of communication link re-establishment between the rack and the supervisory system, and a functional test of representative control loops before returning the system to automatic operation. Documenting the replacement — including the serial number of the installed VT25-373-99/X9 unit, the date of installation, and the technician’s sign-off — supports traceability requirements under maintenance management systems and classification society audit trails.

Retrofit Support FAQ

Q1: Is the KONGSBERG VT25-373-99/X9 a direct drop-in replacement for the original OEM unit?
Yes. The VT25-373-99/X9 supplied by NINERMAS is sourced to match the original OEM specification for the KONGSBERG VT25 series rack. Before installation, verify the rack slot position, backplane connector keying, and output voltage rating against the system documentation to confirm compatibility with your specific rack assembly revision.

Q2: Will replacing the power supply affect the controller program or I/O module configuration?
No. The controller module’s program logic and I/O module configurations are stored in non-volatile memory and are not affected by a power supply replacement or controlled power cycle. As a precaution, export a program backup from the engineering workstation before initiating the replacement, and verify all module status indicators after power restoration.

Q3: What pre-installation checks are required for wiring and terminal compatibility?
Confirm that the existing AC input wiring gauge, terminal block type, and torque specification match the requirements of the replacement unit. Inspect the backplane connector on the rack for signs of corrosion or mechanical damage before inserting the new power supply. If the rack has been in service for an extended period, cleaning the backplane connector contacts is recommended prior to installation.

Q4: What does the 12-month warranty cover, and what is the lead time for in-stock units?
All KONGSBERG VT25-373-99/X9 units supplied by NINERMAS carry a 12-month warranty covering manufacturing defects and functional failure under normal operating conditions. Units are pre-tested prior to shipment. For current stock availability and lead time confirmation, contact our team directly — we maintain inventory of critical KONGSBERG VT25-series spare parts to support urgent retrofit and breakdown replacement requirements.