WCU Ship Control Unit Manual

Use a multimeter to measure the continuity of the contacts and confirm that the actual state is consistent with the configuration.

5.4 Relay output does not operate

Possible reasons:

The software output logic is not enabled.

Relay contact adhesion or coil burnout.

Insufficient driving voltage.

Inspection method:

Force flip the output in test mode and listen for a "click" sound. If not available, measure the voltage at both ends of the relay coil (usually 24V).

If there is voltage but no action, replace the relay (or the entire I/O board).

If the output action is taken but the external load is not working, measure the continuity of the contact end and the load power supply.

5.5 WCU and upper communication interruption

Inspection sequence:

Physical layer: Check for loose cables and connectors. For CAN bus, measure the terminal resistance.

Voltage: Ensure normal power supply to WCU (undervoltage causes communication chip to malfunction).

Address Conflict: Each WCU node must have a unique CAN ID or IP address. Check the dip switch or configuration file.

Baud rate: Confirm that the baud rate of all nodes in the system is consistent (such as 250k).

Bus load: If a large number of nodes frequently send data, it may cause bus conflicts. Use an analyzer to check the bus utilization rate (recommended to be below 50%).

Advanced diagnosis: Use a portable CAN analyzer (such as Kvaser) to monitor the bus and observe for any error frames. If WCU does not send any messages, its communication controller may be damaged.

Maintenance and Periodic Inspection

Although WCU is designed to be maintenance free, it is recommended to perform the following items during annual inspections and daily patrols by classification societies:

6.1 Before each voyage (or every week)

Visual inspection: The shell has no cracks and the indicator lights are in normal condition (power light, communication light).

Touch shell temperature: There should be no obvious burning sensation (normal slight warmth).

Check the tightness of the wiring terminals, especially the power and ground terminals.

6.2 Every three months

Cleaning: Use dry compressed air to blow away dust on the surface of the circuit board (pay attention to electrostatic protection).

Check if the ventilation opening (if any) is blocked.

Perform zero and range sampling on all analog input channels (using a signal generator to inject 4mA and 20mA and verify the displayed values).

6.3 Every year

Tighten all wiring screws to a torque of 0.4-0.5 N · m.

Measure the grounding resistance, which should be less than 0.1 Ω.

Perform communication packet loss rate test: Send 10000 request packets through monitoring software and calculate the timeout rate (which should be less than 0.1%).

Backup the configuration parameters of WCU to external storage (such as USB or server).

6.4 Every five years (or when there are signs of malfunction)

Replace electrolytic capacitors (especially power filter capacitors) - it is recommended to return to the factory for repair.

Replace all plug-in relays (if used).

Update firmware (if there is a new version, it can improve stability).

Environmental violations and enhanced protection measures

The IP22 protection level of WCU means that it can only prevent vertical dripping and cannot withstand water spray or immersion. If installed in a splash prone area of the engine compartment (such as near the cooling water pump), additional protective measures should be taken:

Installed inside a protective box with a sealing strip (recommended IP44 or higher).

Install a water deflector above WCU.

Use anti-corrosion coating circuit boards (which may have been made at the factory, but can be regularly sprayed with three proof paint).

When the humidity exceeds 97% and condensation occurs, even if the WCU itself can work, it may cause oxidation or leakage of the wiring terminals. It is recommended to install a small temperature controlled heater or desiccant inside the control box.

Certification and Compliance Tips

When replacing WCU, it is necessary to confirm that the new module has the same copy of the classification society certificate (the certificate must be accompanied by the ship). For ship changes or new WCUs, the classification society surveyor should be notified to conduct installation inspections and update the equipment list (IED). WCU's type certification covers major classification societies such as DNV, LR, ABS, BV, CCS, etc., so there is no need to certify each project separately. However, the installation drawings and wiring methods must meet the recognized conditions (i.e. comply with IACS E10 and IEC 60945).

Upgrade and spare parts recommendations

Spare part model: Record the complete model of WCU (e.g. WCU-24V-K1). It is recommended to equip at least one spare module (for ocean going vessels).

Compatibility replacement: If the original model is discontinued, a replacement model with corresponding functions, interfaces, and certifications should be selected. Be sure to verify the number of I/O channels, communication protocols, and physical dimensions.

Firmware upgrade: Some ship owners require upgrading WCU firmware through the K-Chief service tool to obtain new features or patches. Before upgrading, it is necessary to backup the configuration and ensure stable power supply during the upgrade process.