As we all know, ships are equipped with a large number of electrical devices, especially in the engine room where various machinery and extensive wiring are densely installed. Alarms of sound and vibration can be found everywhere, reflecting the highly automated and safety‑conscious nature of shipboard operations.
Due to the unique operating environment of vessels, marine power systems mostly adopt an insulated IT system (ungrounded system). Therefore, insulation monitoring is far more stringent and critical on board ships than on land.
Maintaining the proper operation of SU-IR-2002 — the 24‑hour guard for insulation safety — is essential to ensuring the reliability of ship electrical equipment and, more importantly, the personal safety of the crew.
Without the safety and well‑being of seafarers, there can be no secure navigation, let alone economic efficiency. In severe cases, insulation failure may lead to serious marine accidents, casualties, and even severe environmental pollution and ecological damage.
Based on the above-mentioned importance of the SU-IR-2002 insulation relay, our client entrusted us to arrange professional electrical technicians with specialized equipment to board a container ship berthed at Tianjin Port during discharging operations on 02 April 2026.
Part I: Technician Boarding & Briefing from the Ship
After completing all necessary boarding procedures, our two electrical technicians went on board and communicated with the duty crew to understand the general fault condition of the SU-IR-2002 insulation relay:
The insulation device failed to provide normal readings and could not trigger a low-insulation warning, which may lead to electric leakage and create a high risk of electric shock and accidents for the crew.
The ship’s staff suspected that the insulation indicator light and test switch were defective.
Part II: Detailed Troubleshooting by Our Technicians
1. Disconnected each circuit and measured voltage on each loop. No obvious grounding or leakage was found.
2. Tested the 24V switchboard grounding insulation indicator light. Both the indicator light and test switch were confirmed faulty.
3. Purchased and replaced the grounding insulation indicator light, restoring its normal function.
4. Replaced the test switch and carried out a test; the function returned to normal.
5. Tested the input and output of the grounding insulation relay. When a signal was input, no alarm signal was output properly.
6. Purchased and replaced the complete insulation relay. After testing, the output signal functioned normally.
From replacing the indicator light and test switch to finally replacing the entire insulation relay, we successfully resolved the problem and ensured the insulation system worked effectively again.
The potential risk to crew safety and numerous critical electrical equipment on board was extremely serious. It is difficult to imagine the severe consequences if such hidden dangers had not been eliminated in a timely manner.
Part III: Summary Based on This Insulation Relay Service
1. The insulation indicator light and test switch are basic components for monitoring the insulation relay. Their working condition must be ensured normal at all times.
2. The insulation relay was replaced in this service. Such internal faults are difficult to detect if the indicator light and test switch function abnormally.
3. Spare parts for indicator lights, test switches, and especially insulation relays should be kept on board to enable timely replacement and avoid further accidents.
4. Once a fault in the insulation light, test switch, or insulation relay is detected, high alert must be raised to prevent electric shock and equipment damage, and relevant crew members should be informed of the risks.
5. Regular testing and maintenance should be performed to identify such problems at an early stage.
6.Sufficient protective measures and detailed checklists should be prepared before carrying out key electrical operations on board, to enhance safety protection for crew and equipment.
Part IV: Write at last
Every crew member represents a family, working at sea with the best wishes and deep longing of their loved ones. Every vessel carries multiple hopes and expectations, sailing worldwide to support economic development and meet people’s daily needs.
Considering the limited medical support and firefighting equipment on board, any personal injury, equipment breakdown, or even fire caused by electric leakage will bring incalculable losses.
Therefore, we must always attach great importance to insulation safety. Safety is always the top priority.
By the way: For professional onboard sensor calibration at CUD Shipyard, you can refer to *Onboard Sensor Calibration CUD Shipyard* for standard operation procedures.
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