MJHR

ModelMJHR
PowerUp to 11.000 kVA
VoltagesUp to 15.000 V
Frame400 ÷ 1.250
Poles4, 6, 8
(over contact MM)
CoolingIC 81W
IPIP 44. Available up to IP 56.
EnclosureTEWAC - Totally Enclosed Water to Air Cooled
Main ApplicationsSteam & GAS Turbines
SectorCogeneration
  • Poles | kVA | 60 Hz
  • Certificates and testing
  • Main components
  • Construction
  • Technical data
  • Operating conditions
  • Auxiliary device
  • Optional features

Poles | kVA | 60 Hz

4
4
10.000
6
6
12.500
8
8
12.500

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.
Aderence to ISO 8528 group G preformance classes.
Certificate
Certificate
Test Certificate supplied with the machine.
Material certificates in accordance with EN 10204 : 2001 can be supplied.

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 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 – N).
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 on application requirements.
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

Enclosure
Enclosure
TEWAC - Totally Enclosed Water to Air Cooled
Cooling System
Cooling System
IC81W 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.
Other mounting available on request.

Technical data

Stator/Rotor core
Stator/Rotor core
Laminated and enamel-insulated on both sides to minimise eddy-current losses
Rotor
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 are available.
Bearing
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 800 frame size included.
Sleeve bearings from 900 frame size included (available for smaller frame sizes)
Regreasing system:
Up to 400 frame size:
  • D-end bearing is fitted with inner bearing cap and with grease nipple
  • ND-end bearing is prelubricated with inner bearing cap and without grease nipple
450 frame size and above: 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
All ND end sleeve bearings are insulated as standard.
Impregnation system
Impregnation system
Stator and rotor are VPI treated with an unsaturated polyester amide resin which is polymerised in an oven.
Insulation system
Insulation system
Stator: F class insulated with a synthetic enamel (class H option with BH technology).
Rotor: H class insulated with a synthetic enamel.
Protective treatments
Protective treatments
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 a 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 can be designed to meet specific reactance values (x'd and x''d). Values can be confirmed by contacting Marelli Motori.
Three pahse short circuit current
Three pahse short circuit current
All generators equipped with overboosting device ensure a three phase short circuit current (Icc) higher than 3 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
AVR
Automatic voltage regulator mounted on board.
SizeType
400 - 450MEC 20 analog/ digital
500 - 560M40FA610A analog
630 - 710M63FA310A analog
800 - 1.250MEC 100 digital
Digital AVR available for all sizes on request.
Overboosting device
Overboosting device
SizeType
Medium VoltageAllCT + Overboosting device
High voltageAllPMG
Space heaters
Space heaters
SizePower(W)
400 - 560400
630 - 710600
800 - 900800
1.0001.000
1.1201.200
1.2501.400
Heaters installed at ND-end side.
RTD-PT100
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
List
  • Low losses magnetic steel
  • 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.

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