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04/05/2024

UPS fail. Main engine automatic backup does not work. Kongsberg Troubleshooting

The UPS fail error occurred and the final system for protecting the main engine against automatic power failure failed. A BMS AC220V UPS FAIL alarm appeared on the alarm monitoring system in the ECR. BMS - Bridge maneuvering system.

BMS AC220V UPS FAIL
BMS AC220V UPS FAIL

In simple words, the uninterruptible power supply (UPS), which is designed for the normal operation of the automatic control system of the main engine during the transition of the ship's electrical station from main to emergency power, has stopped working.

In this article we will analyze the sequence of actions to resolve this problem. We open the UPS cabinet of the main engine automatic control system and see that there is also an alarm on the uninterruptible power supply.

UPS alarm
UPS alarm
Power unit
Power unit

As always, we refer to the instructions to identify the source of the error.

Circuit of UPS cabinet of the main engine automatic control system
Circuit of UPS cabinet of the main engine automatic control system

According to the instructions, first of all you need to check the condition of the batteries. Since batteries are maintenance-free, it is advisable to use a battery tester to determine the battery capacity.

Troubleshooting
Troubleshooting

To do this, turn off the FB circuit breaker, open the battery cabinet, disconnect the batteries and measure the voltage and capacity.

Kongsberg battery cabinet
Kongsberg battery cabinet
Disconnecting the batteries
Disconnecting the batteries
Testing batteries with battery tester "load fork"
Testing batteries with battery tester "load fork"

The multimeter shows more than 26 V (two 12V 12Ah batteries are connected in series), but the real situation is that the battery capacity is at zero. The photo above shows the battery test using a "load fork".

Testing new batteries with battery tester "load fork"
Testing new batteries with battery tester "load fork"

The batteries need to be replaced. When receiving a set of batteries, we measure the capacity and use the same procedure described above to replace the batteries with new ones. It is very important to switch UPS to Service mode.

Service mode
Service mode

To do this, the UPS battery capacity selection switch must be set to the Service position. After replacing the batteries and turning on the FB breaker, we move the switch to the position of our capacity - 12 Ah.

UPS service has been restored
UPS service has been restored
Alarm "gone"
Alarm "gone"

As a result, we restored UPS of the main engine remote automatic control system. Batteries can be replaced while the vessel is moving, because in normal operation, the automatic control system of the main engine does not use batteries.

In this article, I specifically focused on the battery tester "load fork", because a multimeter only shows voltage, but it is not able to show the real state of the battery, its capacity. The multimeter may show normal voltage, but in fact the battery is no longer working.

By the way, it is not recommended to use a "load fork" on small batteries; it is advisable to use an electronic battery capacity tester. It is also suitable for work on tankers. The loading fork cannot be used on tankers!

Very often in my practice, I observe that on ships with maintenance-free batteries there are no special load forks (battery testers). I recommend to order and use it, otherwise it is impossible to immediately understand what the problem really is, in the battery or in the uninterruptible power supply (UPS).

AMS model: Alarm monitoring & control system Kongsberg K-Chief 500.

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