7 семестр (Бормотов А) / 1man_bw_l23_30_chn_23_30_instruktsiya_po_ekspluatatsii / MAN-BW L23-30 (ЧН 225_300)+ / MAN-BW L23-30h project-guide

1624450-8.2 Page 1 (1)

L23/30H

Mechanical Overspeed

The engine is protected against overspeeding in the event of, for instance, governor failure by means of an overspeed trip.

The engine is equipped with a stopping device which starts to operate if the maximum permissible revolution number is exceeded.

The overspeed tripping device is fitted to the end cover of the lubricating oil pump and is driven through this pump.

If the pre-set tripping speed is exceeded, the springloaded fly weight (1), see fig 1, will move outwards and press down the arm (2).

The arm is locked in its bottom position by the lock pin (3) which is pressed in by the spring (4).

At the same time the arm (2) presses down the spindle (5), and the pneumatic valve (6) opens, whereby compressed air will be led to the stop cylinder, (see also B 17 30 1) in which the piston is pressed forward and, through the arm, turns the fuel pump regulating shaft to STOP position. Thereby the engine stops, the spring-loaded pull rod connection to the governor being compressed.

The engine can be stopped manually by pressing down the button (7), which will activate the springloaded fly weight (1) through the lever (8).

If the overspeed has been activated, the overspeed must be reset before the engine can be started. Reset is done by means of the button (10).

Overspeed Alarm (SAH 81)

The overspeed alarm (SAH 81) is activated by means of the micro switch (9).

1639469-7.2 Page 1 (1)

08028-0D/H5250/94.08.12

Description

The starting box is mounted on the engine's control side. On front of the box there are the following indications/pushbuttons:

–Indication of engine or turbocharger RPM

–Indication of electronic overspeed

–Pushbutton for "Manual Start"

–Pushbutton for "Manual Stop"

–Pushbutton for "Remote" *

–Pushbutton for "Local" *

–Pushbutton for "Blocking" *

–Pushbutton for change-over between engine and turbocharger RPM

*The function chosen is indicated in the pushbutton. See fig. 1.

Manual Start

The engine can be started by means of the start button, but only if the button "Local" is activated.

The manual, local start is an electrical, pneumatic start, i.e. when activating the start button a solenoid valve opens for air to the air starter, thereby engaging the starter and starting the diesel engine. Throughout the starting cycle the start button must be activated.

The air starter is automatically disengaged when the diesel engine exceeds 110 RPM. If the start button is disengaged before the diesel engine has exceeded 110 RPM, further starting cycles are blocked, until 5 sec. after the engine is at standstill.

Remote Start

Remote start can only take place if the pushbutton for "Remote" is activated.

Manual Stop

The "Manual Stop" button is connected to the stop coil on the governor.

Blocking

If "Blocking" is activated, it is not possible to start the diesel engine.

General

Engine / Turbocharger RPM

By activating the "Engine RPM/TC RPM" button, the indication is changed.

Engine RPM indication is green light-emitting diodes and turbocharger RPM indication is red light-emitting diodes.

External Indications

There are output signals for engine RPM and

The pushbuttons for "Remote", "Local" and "Blocking" have potential free switches for external indication.

All components in the starting box are wired to the built-on terminal box.

Fig 1 Starting box.

1635436-4.2 Page 1 (2)

For measuring the engine's RPM, a pick-up mounted on the engine is used giving a frequency depending on the RPM. To be able to show the engine's RPM on an analogue tachometer, the frequency signal is sent through an f/I converter (frequency/current converter), where the signal is transformed into a proportional 4-20 mA ~ 0-1200 RPM.

Both tachometer on the engine and possibly external tachometers should be connected in the current loop.

Further, the converter has following signals:

–overspeed

–engine run

–safe start

–tacho fail

Overspeed

When the engine speed reach the setpoint for electronic overspeed the converter gives a shutdown signal and a alarm signal through a relay.

When the engine speed reach 710 RPM the converter gives a "engine run" signal. The signal will also be given when the engine speed reach 200 RPM + 8 sec., (this is used for pump engines).

The engine run signal will be deactivated when the speed is 640 RPM. If the engine speed haven't been over 710 RPM the signal will be deactivated at 200 RPM.

The "engine run" signals will be given through a relay. One for synchronizing and one for start/stop of pre. lub. oil pump or alarm blocking at start/stop.

Safe start

When the safe start signal is activated the engine can start. When the engine reach app. 140 RPM the air starter will be shut-off.

Further, the safe start signal is a blocking function for the air starter during rotation.

1635436-4.2 Page 2 (2)

General

Tacho fail

The tacho fail signal will be on when everything is normal. If the pick-up or the converter failed the signal will be deactivated. E.g. if there is power supply failure.

The converter for engine RPM signal is mounted in the terminal box on the engine.

Pick-up

The pick-up is a NPN-type with LED-indication. The sensing distance is 0.5 to 1.2 mm.

All wiring to relay, pick-up and tachometer are made by MAN B&W, Holeby.

Data

1631457-0.0 Page 1 (2)

The Safety System

The engine control box is watching the most important safety operating functions of the diesel engine, i.e. low lub. oil pressure, high cooling water temperature, and overspeed.

If an unintended condition occurs to one of the above functions, the engine control box will release automatic stop of the engine (shut-down).

In order to avoid an unintended re-starting after release of a shut-down, there is a built-in reset function which has to be activated before the engine can be re-started. Remote reset is also possible.

Besides, there are built-in start/stop procedures for the engine. On fig. 1 the possible external connections and input/output signals are shown.

On the front cover of the engine control box there are an indication panel.

There are indications for:

-Power

-Lub. oil shutdown

-High temp. fresh water shutdown

General

-Overspeed shutdown

-Start failure

-Wire break

-Start interlocks

There are push buttons for:

-Start

-Stop

-Reset

-Lamp test

Alarm Blocking

The engine control box is provided with a relay output for alarm blocking. It is advisable to use in case of too low lub. oil pressure, so that alarm is avoided during starting and stopping of the engines.

Start/Stop of the Diesel Engine

As the engine control box can give the diesel engine a signal of normal start/stop, it is possible to mount remote switches for these functions.

08028-0D/H5250/94.08.12

General

1631457-0.0 Page 2 (2)

If the diesel engine does not start during a starting trial, a potential free switch will give the information that there is a starting failure.

When the diesel engine is running. Two relay outputs are activated. One of these switches can be used for start/stop of the prelubricating pump.

Engine Control Box Cabinet

The engine control box cabinet can be installed in the engine room, near the engine, fig. 1 shows the dimensions of the cabinet.

Enclosure: IP 55.

The engine control box can also be installed in the engine control room. It is possible to integrate the engine control box in the switch board.

The following is available as an option:

-One box for 3 engines

-Electronic overspeed

-Custom made solutions

08028-0D/H5250/94.08.12

1643403-4.0 Page 2 (2)

General

The push buttons for MDO and HFO are lighten push buttons to indicate the mode.

Engine Control Box Cabinet

The engine control box cabinet can be installed in the engine room, near the engine. Fig 1 shows the dimensions of the cabinet.

Enclosure: IP 54.

The engine control box can also be installed in the engine control room. It is possible to integrate the engine control box in the switchboard.