How to read electrical diagrams on a ship? Main engine turning gear operation diagram

Greetings! You have motivated me to write this article. Thank you for your comments to the previous article "Installing a timer in the electrical diagram of the main engine turning gear" and in social network groups. In fact, writing such articles takes a lot of time and effort, so motivation and support are needed. And it is enough to just write a positive review ;)

In this article I will try to explain in simple language the principle of reading electrical circuits on a ship using the example of the main engine turning gear device.

If you understand this diagram, it will help you read more than 60% of the circuit diagrams on a ship.

Attention! This article is aimed at beginners who are just learning to read electrical circuit diagrams. In the article you will encounter various questions from the author, to which it is advisable to find answers for practical mastery of the material.

The turning gear device diagram can be classified as a category of ship electric drive operation diagrams.

Electrical diagram of the main engine shaft turning device

On each vessel, you can encounter hundreds or more electric drives that operate on approximately the same principle to one degree or another. Depending on the mechanism and system in which the electric drive is installed, their diagrams may differ in operating modes, as well as protection and signaling circuits.

Where to start reading an electrical diagram?

So, to begin with, let's divide this diagram into two parts, the power and the control circuit, which also has a signaling and protection circuit.

Power section of the circuit

Control and protection circuit

Power part of the circuit

On the power part of the circuit we see an image of power lines L1, L2, L3 (three phases 440V), which go from the distribution board (in the diagram it is simply POWER SUPPLY) to our electric motor, but the cable does not go directly to the motor, on its way there are automatic switches, power contacts of contactors, as well as thermal protection (thermal relay). Numbering 1, 2, 3 is the numbering of cables in the starter board. Numbering L1, L2, L3 is the numbering of the contact group on the terminal.

In the photos below you can see the installed timer, its operation was described in the previous article. We will not consider it here.

Starter panel

Starter panel (inside)

Starter panel (inside)

Circuit breakers F1, F3, F4

In order, what we see in the diagram:

• Q1 - three-pole circuit breaker, it is visible from the outside of the starter (red switch).
• F1 (10A) - three-pole circuit breaker for 10 amps, located inside the panel.
• P1 (A) - ammeter on phase L1, connected in series (7 - 10).
• T1 - step-down transformer (it has two secondary windings, one for 24V, the second for 220V). The transformer is required to reduce the voltage in the control and signaling circuit.
• 1KM and 2KM are contactors for starting the electric motor. One is in the "AHEAD" mode, i.e. forward, the second in the "ASTERN" mode, i.e. backward. The circuit shows that to implement the reversal of the electric motor, cables 9 and 10 (two phases) were connected differently, on the 1KM contactor they are connected (9 - 13) and (10 - 11), and on the 2KM contactor - (9 - 11) and (10 - 13), i.e. vice versa. This is how the reversal of the electric motor is implemented. Although it is enough to swap only one phase to organize the reversal of the electric motor. Next to the power contacts of the 1KM and 2KM contactors, their contacts in the control circuit are shown (i.e. two normally closed NC contacts and one normally open NO contact).
• F2 - thermal protection (thermal relay), here the power contacts pass through the bimetallic plates of the thermal relay, which, when the electric motor is overloaded above the set protection current, will instantly open (close) their contacts in the motor control circuit. How many bimetallic plates are in the thermal relay? In this case, the thermal relay F2 (coil power supply 41 - 29) can be found in the control circuit, as well as its two F2 contacts. The first contact F2 (41 - 30) will close when the protection is activated and the OVERCURRENT lamp will light, the second contact F2 (41 - 31) will open and the entire control circuit will be disconnected, including the 1KM and 2KM power contactors of the M1 motor. M1 - turning gear electric motor. The motor has a winding heater. By the way, it is because of the heater that a step-down transformer is installed here for two secondary windings. The heat source requires 220 volts, and the control and signaling circuit requires 24 volts.
• PE - protective earth (motor grounding).

Elements of the turning gear device circuit

Control and protection circuit

• F3 (4A) - a two-pole 4-amp circuit breaker, protects the transformer and control circuit from current overload, for example, from short-circuit current.
• F4 (4A) - a two-pole 4-amp circuit breaker, protects the transformer and heater.
• 1KM (22 - 24) and 2KM (24 - 25) - NC contacts in the heater circuit. When the coil of the 1KM or 2KM contactor receives power, these contacts open the heater circuit so that it does not work during engine operation.
• P2 BLUE - blue heater operation light.
• 28 - 41 - jumper. The circuit provides for modification - you can add a remote stop button FOR EXTERNAL STOP (OPTION), for example, in the ECR. To do this, remove the jumper and connect a cable to the stop button with an NC contact, which will open when the button is pressed and, accordingly, stop the motor.
• P3, P4, P5, S3P, S4P, P6 - lamps on the starter panel. Accordingly, P3 - power supply for the entire circuit, P4 - motor overload by current, P5 - local control, S3P - motor operation "forward", S4P - motor operation "backward", P6 - remote control using the remote control.
• H01 - remote control power lamp when the toggle switch S1 (31 - 32) is switched to REMOTE.
• S2 (NC 32 - 34) - motor stop button on the starter panel. Opens the power supply for contactors 1KM (29 - 39) and 2KM (29 - 40).
• S3 (NO 34 - 35) - motor start button "forward". NC (34 - 36) contact opens the motor operation circuit "back".
• S4 (NO 36 - 38) - motor start button "back". NC (35 - 37) contact opens the motor operation circuit "forward".

How does the circuit work?

Now, based on the above, we will describe the circuit operation. The circuit is in LOCAL mode - switch S1 is in the MAN position, contact 31 - 32 is closed, the yellow light P5 - LOCAL CONTROL is on. In this case, all protections are armed (not knocked out), the white light P3 is on - the circuit is ready for operation. The contact of the thermal relay F2 (41 - 30) is open - the red light P4 is not on. Contact - F2 (41 - 31) is closed, accordingly the light P5 - LOCAL CONTROL is on.

Contactors 1KM and 2KM

The operator presses the S3 - AHEAD button:

• The contact of the S3 button (34 - 35) closes, the 1KM contactor receives power, which closes its power contacts (10 - 11, 8 - 12, 9 - 13) and the motor receives power and runs "forward". The 1KM contact (34 - 37) also closes, which bypasses the S3 button so that it does not have to be held. The circuit of the S4 button (35 - 37) and the 2KM contact (37 - 39) is closed. The 2KM contact is closed, since the 2KM contactor does not receive power.
• The contact of the S3 button (34 - 36) opens, which additionally opens the circuit of the 2KM contactor.
• The NC contact of the 1KM contactor (38 - 40) also opens, since contactor 1KM receives power. Thus, the circuit of contactor 2KM is open in three places: S3 (34 - 36), S4 (36 - 38) and 1KM (38 - 40). This is done to protect the circuit and motor from incorrect operator actions, or from failure of some section of the circuit.
• The motor runs forward, the coil of contactor 1KM constantly receives power, since the start button S3 is shunted.
• When the stop button S2 is pressed, the coil of contactor 1KM loses power, the motor stops and the circuit returns to its original state.

The operator presses the S4 - ASTERN button:

• The contact of the S4 button (36 - 38) closes, the 2KM contactor receives power, which closes its power contacts (10 - 13, 8 - 12, 9 - 11) and the motor receives power and works "backward". The 2KM contact (34 - 38) also closes, which bypasses the S4 button so that it is not held. The circuit of the S3 button (34 - 36) and the 1KM contact (38 - 40) is closed. The 1KM contact (38 - 40) is closed, since the 1KM contactor does not receive power.
• The contact of the S4 button (35 - 37) opens, which additionally opens the circuit of the 1KM contactor.
• The NC contact of the 2KM contactor (37 - 39) also opens, since the 2KM contactor receives power. Thus, the circuit of the 1KM contactor is open in three places: S4 (35 - 37), S3 (34 - 35) and 1KM (38 - 40). This is done to protect the circuit and the motor from incorrect operator actions or from failure of some section of the circuit.
• The motor runs backwards, the coil of the 2KM contactor is constantly powered, since the start button S4 is shunted.
• When the stop button S2 is pressed, the coil of the 2KM contactor loses power, the motor stops and the circuit returns to its original state.

Switching the circuit to REMOTE CONTROL

We switch the circuit to REMOTE CONTROL using switch S1, its contact (31 - 33) closes, contact (31 - 32) opens, the P5 (29 - 32) - LOCAL CONTROL lamp goes out, the P6 (29 - 33) - REMOTE CONTROL lamp lights up.

Electric drive control panel in REMOTE mode

The control panel is turned on, the power lamp of the H01 control panel lights up, because the emergency stop button with mechanical lock S01 is released and closes its contact. Buttons S02 and S03 work the same way as buttons S3 and S4, so I will not describe their operation in detail. That is, button S02 activates contactor 1KM, and button S03 activates contactor 2KM. When you press the stop button S01, the control circuit of the control panel loses power.

Attention! In this article, I deliberately made one minor mistake in describing the operation of the circuit. I hope you will find it ;)

So where should I start reading the circuit?

Above I wrote that the circuit should be divided into two parts, the power and control circuit, but you need to start reading the circuit from the control circuit, namely from the starting part and the protection circuit.

If you have some kind of malfunction, you do not understand what is happening, why the motor does not start, and the lights do not light (maybe they burned out), which usually help to determine the direction of the search, then take the circuit, find the "start" button and measure the voltage on it.

If there is no required voltage, then follow the circuit and look for which protection has worked and does not supply power to the button. If you are working with a de-energized circuit, then you need to check the resistance of the circuit sections to the button and look for what gives a break. Perhaps this is a contact of a thermal relay, or maybe a contact of a float or a pressure sensor, or maybe the button itself does not work, there are many options ...

By the way, what voltage in this case comes to the S3 button in the normal state of the circuit and what will be the voltage on the same button if the thermal relay is activated?

Electrical circuits on Japanese ships

The circuit we discussed above is taken from a Chinese-built ship. And here is a minus: it is general (not fully adapted to a specific ship) and the numbering on the circuit does not fully match what we see in the panel. For an experienced ETO, this is not a critical problem, although there is some discomfort. It is a different matter on Japanese-built ships, where the numbering of cables and terminals strictly matches what is in the starter panel.

Main engine turning gear device on a Japanese vessel

I offer you a electrical diagram of the turning gear device on a Japanese vessel. Please note that the factory installed timer in this diagram, in addition, the electric motor uses an electromagnetic brake on direct current.

Electrical diagram of the operation of the shaft-turning device on a Japanese vessel

Photos of the starter panel of the shaft-turning device on a Japanese vessel

The Japanese circuit is not very different from the Chinese one, the only thing is that it has a TM timer (30 minutes) and a BRAKE CONTROL UNIT AC220V / DC90V, which is involved in the electromagnetic brake circuit. By the way, here the timer is involved in two circuits AHEAD and ASTERN, unlike my modification, where the timer only works in the AHEAD circuit. You can download the Japanese circuit in the original pdf format at the link.

If you have any questions, want to consider some other circuit or you have found mistake in the description of this circuit, then write in the comments to this article. I will actively participate in the discussion :)

You can download the Chinese circuit in the original pdf format at the link.

P.S. It turned out that on our website you can also find a turning gear device circuit from a Korean vessel. It is in the article: "Phase fail. The turning gear and the LO autofilter of the main engine do not start". I hope this article was useful to you! Thank you for your attention!