ELECTRICAL EQUIPMENT

Generating Plant
The electrical power generating plant consists of the following:

Main Diesel Generators

No. of sets: 4
No.1 and No.4: 6,600V AC, 3-ph, 60Hz, 7,530kW, 778.5A,8,900kVA
No.2 and No.3: 6,600V AC, 3-ph, 60Hz, 5,650kW, 583.6A,6,670kVA

Emergency Diesel Generator

No. of sets: 1
Rating: 450V AC, 3-ph, 60Hz, 750kW, 937.5kVA

Main Switchboards

Manufacturer: Hyundai

Introduction

The main power generating plant of the vessel consists of four diesel-driven generator sets. The generators supply 6,600V at 60Hz to the port and starboard 6.6kV main switchboards (HM1 and HM2).The main network consists of two 6.6kV main switchboards, two 6.6kV cargo switchboards (HC1 and HC2), two 440V main switchboards (LM1 and LM2), two 440V cargo switchboards (LC1 and LC2) and the 440V emergency switchboard (ES).

Electrical Distribution

6.6kV Switchboards

The two main 6.6kV switchboards are normally connected together by transfer line and so constitute a common bus. This main bus feeds the highvoltage consumers, the propulsion system and the cargo 6.6kV switchboards.The 6.6kV main switchboard diesel generator panels are each equipped withan ammeter, a voltmeter and a frequency meter. Each generator panel is also equipped with a Hyundai HIMAP BC protection, operation and display unit.This unit is the operator interface for the generator and the Power Management System (PMS). Local or remote control is indicated on the synchronizing panels by the IAS CONTROL MODE signal lamp. The synchronizations are fitted with generator watt meters, dual frequency meters, dual voltmeters, synchroscope and synchronising lamps for manual synchronising and connection of generators.

440V Switchboards

The 6.6kV main switchboard supplies the 440V low voltage switchboards (LM1 and LM2) via the use of two transformers (MT1 and MT2) or througha single transformer and a bus-tie connection between LM1 and LM2. These 440V switchboards in turn supply the engine room machinery.During normal operation, the 440V bus-tie line will remain open and each 440V switchboard will be supplied from the respective 6.6kV switchboards viaa 6,600/440V transformer.The emergency switchboard is supplied from the 440V main switchboards LM1 or LM2, .

Emergency Switchboard

A separate emergency network supplies essential consumers in the event ofa loss of power on the main switchboards. The emergency switchboard is supplied from the main 440V electrical distribution system. The feed breakers for this are interlocked so that only one 440V switchboard, LM1 or LM2 can supply the emergency switchboard at one time, the emergency generator circuit-breaker is also interlocked with these breakers.The emergency generator supplies the emergency switchboard if the supply from the main 440V switchboards fails.

High Voltage Cargo Switchboards

The 6.6kV main switchboards supply power to the two 6.6kV cargo distribution switchboards, HC1 and HC2. Each cargo switchboard is supplied from a separate main switchboard via bus-ties. The two 6.6kV cargo switchboards may also be interconnected to form a common switchboard by the closure of the bus-tie. During normal operation, the bus-tie between the two 6.6kV cargo switchboards will be open and each cargo switchboard is supplied separately from the respective main 6.6kV switchboard. An interlock prevents the cargo switchboard bus-tie breakers and all feeder breakers from being closed for a prolonged time. If the cargo switchboards are both live via the cargo switchboard bus-tie, the feeder breaker HM1 HC1 or HM2 HC2 can be closed for a short period to allow for changing system configuration.

440V Cargo Switchboards

Each 6.6kV cargo switchboard supplies a 440V cargo switchboard via dedicated 6,600/450V transformers CT1 and CT2.

Propulsion Electrical Network

The ship’s propulsion system consists of two propulsion motors, each supplied from a separate propulsion converter. Each 6.6kV main switchboard has two circuit-breakers, each feeding a propulsion transformer. The No.1 6.6kV switchboard supplies the No.1 propulsion converter via the propulsion transformers (ST1 and ST2). The No.2 6.6kV switchboard HM2 supplies the No.2 propulsion converter via propulsion transformers (ST3 and ST4). The propulsion converters each drive a propulsion motor, both drive a single PEMS propeller shaft through a reduction gearbox.

Transformers

No.1 and No.2 6.6kV Main Transformers (MT1 and MT2)

The 6,600V at the 6.6kV main switchboards is transformed down to 440V via two 6.6kV main transformers to feed the 440V main switchboards.

Manufacturer: Hyundai

Type: Cast resin
Capacity: 4,200kVA
No. of sets: 2
Voltage Primary/secondary: 6,600/450V
Current Primary/secondary: 367.4A/5,388.6A
Insulation class: F
Cooling: AN (Air – Natural)
Protection level: IP44

No.1 and No.2 6.6kV Cargo Transformers (CT1 and CT2)

The 6,600V at the 6.6kV cargo switchboards is transformed down to 440V via two 6.6kV cargo transformers to feed the 440V cargo switchboards.

Manufacturer: Hyundai
Type: Cast resin
Capacity: 1,400kVA
No. of sets: 2
Voltage Primary/secondary: 6,600/450V
Current Primary/secondary: 122.5A/1,796.2A
Insulation class: F
Cooling: AN (Air – Natural)
Protection level: IP44

No.1 and No.2 General Transformers (LM1 and LM2)

The No.1 and No.2 main switchboard 220V feeder panels are each supplied via 440/220V transformers.

Manufacturer: Hyundai
Type: Drip-proof floor-mounting dry-typ
Capacity: 220kVA
No. of sets: 2
Voltage Primary/secondary: 440/230V
Current Primary/secondary: 288.7A/552.2A
Insulation class: F
Cooling: AN
Protection level: IP-23

Emergency Transformers (ET1 and ET2)

The 440V at the emergency switchboard is transformed down to 220V via one of two emergency transformers to feed the 220V section of the emergency switchboard.

Manufacturer: Hyundai
Type: Drip-proof floor-mounting dry-type
Capacity: 170kVA
No. of sets: 2
VoltagePrimary/secondary: 440/230V
Current Primary/secondary: 223.1A/426.7A
Insulation class: F
Cooling: AN
Protection level: IP-23

Focsle Transformer

To reduce transmission losses, a 440/230V transformer is fitted to supply 220V consumers at the forward end of the vessel.

Manufacturer: Hyundai
Type: Drip-proof floor-mounting dry-type
Capacity: 30kVA
No. of sets: 1
Voltage Primary/secondary: 440/230V
Current Primary/secondary: 68.2A/130.4A
Insulation class: F
Cooling: AN
Protection level: IP-23
Bank capacity: 90kVA
Voltage Primary/secondary: 440/230V
Current Primary/secondary: 118.1A/225.9A

6.6kV Consumers

The 6.6kV ballast pumps, water spray pump, regas sea water pumps and glycol water pumps are all supplied via 6.6kV vacuum contactors in the main 6.6kV switchboards. The main distribution transformers, propulsion transformers inter connectors and main generators are connected to the 6.6kV main switchboards via vacuum circuit-breakers (VCB). These VCBs are fitted with an earthing device (knife switch) which will earth the outgoing circuit.

440V Motor Starters

The 440V motors are generally of the fan-cooled, squirrel cage induction type with a standard frame designed for AC 440V three-phase 60Hz supply. They are controlled using the direct on-line starting method. The motor starters are generally arranged in Group Starter Panels (GSP) or Local Group Starter Panels (LGSP). Group starter panels are located on each 440V main switchboard and nine local group starter panels (LGSP-1 to LGSP-9) are located throughout the vessel, however, LGSP 1 and 2 are split in to two (A and B). There are several items of equipment started via individual starters.

Steering Gear Motors

The steering gear has two steering gear starters fitted (port and starboard), one for each motor (No.1 starboard and No.2 port).
• No.1 steering gear starter is supplied from the main 440V feederpanel No.1 (circuit P-LC-1M-5).
• No.2 steering gear starter is supplied from the emergency 440V feeder panel (circuit P-LC-EM-1).

Sequential Restarting

After a blackout, the IAS will automatically restart the required machinery to restore normal conditions to the vessel. To fulfil this requirement, at least one diesel generator must be left in the automatic standby mode. The essential Machinery is started automatically according to a specific sequence.

Preferential Tripping

Non-essential loads are interrupted automatically in the case of an over current on any one of the main generators. This provides continuity of supply to the essential consumers.