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09/05/2024

The 220V emergency equipment transformer was tripped. Actions of the ETO on the vessel

Greetings! Today we have switched off all 220V emergency equipment on the vessel, including 220V emergency lighting. In this article we will analyze the cause of this breakdown, as well as ways to find and fix the problem.

The 220V emergency equipment transformer was tripped. Actions of the ETO on the vessel
Service emergency transformers 440 / 220 V

In this situation, it is necessary to immediately check the emergency distribution board, which contains all the automatic switches (breakers) for emergency power sources on the ship.

First of all, we are interested in the circuit breakers of the primary and secondary windings of the emergency service transformer. On the panel we can see that the primary winding circuit breaker of the 440V transformer was tripped and the overcurrent relay was activated.

Emergency distribution board 220VEmergency distribution board 220V
Emergency distribution board 220V
Primary winding circuit breakers 440 V (circuit breaker is on)
Primary winding circuit breakers 440 V (circuit breaker is on)
Secondary winding circuit breakers 220 V
Secondary winding circuit breakers 220 V

A short circuit occurred in the emergency equipment circuit, and the circuit breaker of the primary winding of the 440V transformer was tripped. After further investigation and information from the captain's mate, it turned out that the blackout occurred while all the exterior lighting on the vessel was turned on.

Current protection relay
Current protection relay

We can conclude that a short circuit occurred in the 220V emergency lighting circuit, which contributed to the operation of the current protection. Thus, as a result of checking and sequentially disconnecting all 220V emergency lighting circuits, a short circuit was discovered in the lifeboat deck lighting floodlight.

After disassembling the floodlight, it turned out that a short circuit had occurred in the contact group of the lamp socket.

Disassembling the floodlight (water inside)
Disassembling the floodlight (water inside)
Melted lamp base
Melted (burnt) lamp base
Lamp socket
Lamp socket
Burnt out contacts of the lamp holderBurnt out contacts of the lamp holderBurnt out contacts of the lamp holder
Burnt out contacts of the lamp holder
Installing a new floodlight
Installing a new floodlight

The photos above show that the contact group of the floodlight holder burned out and the phases shortened with each other.

A natural question arises: can such a problem completely de-energize the entire service emergency transformer, why was the breaker of only secondary winding not tripped, which directly cuts off only this floodlight. Apparently the short circuit current was so large that it immediately tripped the primary winding of the transformer without any time delay. This is how the transformer protection relay works.

Emergency service transformer data  Typically, a ship has four 440/220 V service transformers. The main two (main) and emergency two (emergency) 440/220 V transformers provide power to 220-volt consumers, which usually include lighting, chargers, fire alarms, and various consoles in the vehicle. and on the bridge, and other auxiliary equipment 220 V.
Emergency service transformer data

Typically, a ship has four 440/220 V service transformers. The main two (main) and emergency two (emergency) 440/220 V transformers provide power to 220 volt consumers, which usually include lighting, chargers, fire alarm systems, and various consoles in the engine room and on the bridge, and other auxiliary equipment 220 V.

Emergency consumers 220V
Emergency consumers 220V

One main and one emergency transformer are always running, the other two are backup. If one transformer fails, you can switch to a backup one.

Overcurrent relay operating diagram

Overcurrent relay operating diagram

Overcurrent relay operating diagram
Overcurrent relay operating diagram

All this is done manually; in the photo of the circuit breakers you can see the mechanical blocking of the circuit breaker of one transformer, so they cannot work at the same time.

The protection relay has tripped
The protection relay has tripped

When the circuit being measured is overloaded, the current protection relay acts on the shunt relay of the circuit breaker and trips the circuit breaker. The circuit diagrams above show how these relays work.

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