MJRM

Model	MJRM
Power	Up to 6.500 kVA
Voltages	Up to 690 V
Frame	250 ± 900
Poles	4, 6, 8, 10 and 12 (over contact MM)
Cooling	IC 81W/ IC 86W
IP	IP 44. Available up to IP 56.
Enclosure	TEWAC - Totally Enclosed Water to Air Cooled.
Main Applications	Auxiliary generator, Hybrid machine, Off-shore and variable speed generator, Propulsion generator, Shaft generator
Sector	Marine

Poles | kVA | 60 Hz
Certificates and testing
Main components
Construction
Technical data
Operating conditions
Auxiliary device
Optional features

Poles | kVA | 60 Hz

4	4 4.000
6	6 5.000
8	8 6.500
10	10 6.000
12	12 5.400

Certificates and testing

Applicable standards	Applicable standards Generators are designed in compliance with: IEC EN 60034 - 1 BS 4999 - 5000 VDE 0530 NF 51 - 100 NF 51 - 111 OVE M - 10 NEMA MG 1.32 Generators conform to EU rules. UL/CSA certifications available on request.
Certificate	Certificate Marine Survey Certificate supplied with the machine. Marelli Motori has the ABS design assessment. Shaft, housing (propulsion) and exchanger are certified by the Marine Classification Society.

Main components

Housing	Housing Rigid frame, rugged welded steel fabrication (EN 10025 - S235 JR). Frame is provided with side ribs to increase the strength. Marelli Motori generators for continuous duty operation are designed to meet vibration levels per IEC 60034-14, ISO 10816-1 and BS 5000-3.
Shield	Shield Made of spheroidal graphite cast-iron (EN 1563) or grey cast-iron (EN 1561) up to 630 frame size. Made of structural steel (EN 10025 – S235 JR) above.
Shaft	Shaft General data Made in carbon steel and obtained by lamination (EN 10083–2 C40–TN). Shaft is obtained by forging from 290 mm diameter and above. The shaft is tested at the manufacturer in order to check it is defect-free. Shaft design Double bearing generator: cylindrical shaft with key.
Main terminal box	Main terminal box Mounted on side (right or left will be selected). Made of formable steels EN 10130.
Fan	Fan Made of aluminum alloy (EN 1706) or structural steel (EN 10025 – S235 JR) depending upon application requirments.
Heat Exchanger	Heat Exchanger Construction Mounted on top of alternator. Double tube made of CuNi 90/10. Copper fins housing. Equipped with water leakage detector. Exchanger data Designed pressure 6 bar test pressure 10 bar power: up to 200 kW water flow: up to 18 m3/h max glycol: 30% type of water: fresh water or marine (salt) water flanges: PN6 – PN10 – Special (ANSI) Position can be adjusted to site conditions.

Construction

Cooling System	Cooling System IC 81W as per IEC60034-6. Primary fluid (water) is flowing by external water system. Internal air is flowing by a fan mounted on the shaft of the generator at the driven side.
Degree of protection	Degree of protection IP 44 as per IEC60034-5. (Available up to IP 56)
Mounting	Mounting Horizontal - IM 1001 or IM 1101 as per IEC 60034-7

Technical data

Stator/Rotor core

Laminated and enamel-insulated on both sides to minimise eddy-current losses.

Rotor

Salient pole type.
Made by copper flat wire.
H class insulated with enamel coating.
Winding retaining by pass-through bars of high quality steel.
Rotating rectifier: Graetz diode bridge with 6 diodes.
Rotors are dynamically balanced with a half key applied to the shaft extension in accordance with IEC 60034-14 to vibration grade normal A.
Special vibration level construction is available.

Bearing

General data
Single or double antifriction bearing grease lubricated (ball or roller type) or oil lubricated sleeve bearing.
The theoretical lifetime of bearings, L10h according to ISO 281/1 standard, of standard horizontal construction generators, without external forces (radial and / or axial) is in excess of 50.000 hours. On request, the lifetime of bearings, L10h can be in excess of 100.000 hours.
Locating bearings are on the D end side and floating bearings on the ND end side.
Bearing selection
Antifriction bearings up to 560 frame size included.
Sleeve bearings from 630 frame size included (available for smaller frame sizes).
Antifriction bearings can be mounted on 630/710 frame size according to site working conditions.
Regreasing system (for antifriction bearing)
Both bearings are fitted with grease nipple.
Bearing insulation
ND end bearing can be insulated to prevent any harmful circulating current from passing through the bearing surfaces.
Insulated antifriction bearings in standard configuration:

4, 6 poles: insulated ND end bearing from 630 frame size
8 poles: insulated bearing from 400 frame size
10 poles: insulated bearing from 500 frame size

All ND end sleeve bearings are insulated as standard. All configurations are designed to withstand the following marine inclination.

Static		Dynamic
List	15°	Rolling	±22.5°
Trim	5°	Pitch	±7.5°

Dedicated constructions available for different values.

Impregnation system

Stator and rotor are VPI treated with an unsaturated polyester amide resin which is polymerised in an oven.

Insulation system

Stator: H class insulated with a synthetic enamel (class F standard for generators with H>=800 or form wound form H=400. Class H option with BH technology).
Rotor: H class insulated with a synthetic enamel.

Protective treatments

Specific marine treatment.
Epoxivinilic and polyacrylic. Total minimum thickness 120 micromillimeters.
Epoxivinilic: Epoxy two component products, with vinyl change.
Polyacrylic: Two components polyurethane product formulated with unmodified hydroxyl acrylic resin.

Operating conditions

Overloads	Overloads During continuous duty (S1), the following overloads are allowed: 10% for 1 hour 15% for 10 minutes 30% for 4 minutes 50% for 2 minutes These overloads must be occasional and followed by one hour of running at normal load or less.
Parallel operations	Parallel operations All generators are provided with an amply sized damper cage and are suitable for parallel operations with other generators, when equipped with the paralleling unit. A power factor regulator (to work in parallel with the main) is available on request.
Transient ratings	Transient ratings All generators comply with marine rules regarding transient performance. The voltage drop due to the application of 60% of nominal load is within 15%.
Three pahse short circuit current	Three pahse short circuit current All generators equipped with an overboosting device ensure a three phase short circuit current (Icc) higher than three times the rated current (In): Icc > 300% In
Radio interference	Radio interference All generators are equipped with Class B Group 1 radio interference filters as defined by EN 55011.
THD (Total Harmonic Distortion)	THD (Total Harmonic Distortion) The no-load voltage wave form is sinusoidal with THD content less than 2%.
Vibrations	Vibrations Vibration level is in accordance with ISO 10816. Measurement, evaluation and limits of vibration severity are in accordance with IEC 60034-14.

Auxiliary device

AVR

Automatic voltage regulator mounted on board.

Size	Type
250	MARK V analog
315 - 450	MEC 20 analog/ digital
500 - 560	M40FA610A analog
630 - 710	M63FA310A analog
800 - 900	MEC 100 digital

Overboosting device

	Size	Type
Low voltage	250 - 450 (4 poles)	Auxiliary winding
	400 - 450 (>4 poles)	Varicomp
	500 - 710 (all polarities)	Varicomp
	800 - 900	PMG

Space heaters

Heaters installed at ND end side.

Size	Power (W)
400-560	400
630 - 710	600
800 - 900	800

RTD-PT100

RTD devices in standard configuration:

1+1 RTD on each phase of stator winding
1 RTD on each bearing

Terminals in auxiliary terminal box.
Other configurations available:

DUPLEX type
RTD for inlet / outlet air
RTD for inlet / outlet water

Optional features

List

Reinforced construction for high linear vibrations
flanged shaft for direct coupling with engine flywheel (in case of single bearing solution)
neutral point terminals in separate terminal box
terminal box inside air duct (internal terminal box)
cooling system IC 86W with additional forced ventilation
cooler mounted on side
increase protection degree up to IP 54, IP 55 or IP 56
lifted feet to couple the generator with engine on existing baseframe
redundant rotating rectifier with 12 diodes
insulated bearing and earthing brush
AVR supplied loose
automatic power factor control (analog type)
digital AVR MEC100 for frame 400 – 710 (supplied loose)
digital AVR MEC100D with diode failure monitoring
redundant AVR system
excitation/overboosting PMG mounted on generator
lubrication system for sleeve bearing
other options available on request.