795F AC Off-Highway Truck Electric: Electric Power Generation : Generator

Generator

The Generator mounted between the truck frame rails

The power for the Electric Drive Train System on the 795F AC is created by the Generator. The Generator is isolation mounted between the frame rails forward of the rear axle housing. The Generator is coupled to the Engine by a torsional rubber coupling and a driveshaft with universal joint connections on each end.

The Generator will rotate at the same speed as the Engine which is 1800 rpm at full throttle. Consequently, no speed sensors are installed on the Generator. The Drivetrain ECM monitors the engine speed and will use this data to determine the speed of the Generator.

The eight pole synchronous Generator is rated at 2410 kilowatts at 1800 rpm full load. Maximum speed at no load (in neutral or when dumping) is 1960 rpm.

At 1800 rpm, the Generator produces three phases of AC voltage at a level of 1930 VAC line to line.

The voltage and electrical current produced by the Generator will determine the amount of power that is available for the two traction motors.

The Generator consists of the following main components:

Generator Stator Assembly

Generator stator windings (rotor removed)

The stator is a part of the Generator housing. Interior slots that are cut into the housing contain the stator or armature phase windings. The windings are coated with a resin insulation and are isolated from the stator housing. The stator windings are connected in a configuration that will produce the three phases of AC voltage output. The voltage is created by the rotation of the DC charged main rotor windings.

Generator Rotor Assembly

Generator rotor assembly removed - the rotating rectifier is covered in this view (1) Main rotor (2) Exciter stator assembly(2A) Exciter field winding

The Generator rotor assembly is the rotating part of the Generator that is built around the Generator shaft. The main rotor (1) contains the DC field windings that will induce the AC current into the stator windings as the rotor is rotated.

Exciter Stator Assembly

The Exciter Stator Assembly (2) is a second stator assembly that is located in front of Generator Rotor Assembly on the shaft. The Exciter Stator Assembly is bolted to the front-end plate of the Generator and does not rotate with the rotor.

The assembly contains the exciter field winding (2A) that is wound around iron cores. The DC field winding leads are connected to the positive and negative Generator Excitation Field Regulator (EFR) current output circuits. The current that is sent to the field windings from the EFR determines the strength of the magnetic field.

The amount of EFR DC output current that is sent to the pole windings is determined by Drivetrain ECM commands to the EFR. This DC current from the EFR creates the magnetic field in the exciter field windings. The greater the DC current from the EFR, the greater the magnetic field which will result in greater voltage output from the Generator.

Exciter Rotating Assembly

Exciter rotating assembly (3) Ring resistor (4) Rotating exciter armature three phase windings(5) Rotating rectifier assembly

Rotating rectifier diode connections and the connections to the exciter armature and the main rotor windings (6) Diode base leads. - The three base leads on the red diodes in the assembly are anode (+) connections to the conductive DC positive rotating plate. The three base leads on the black diodes in the assembly are connections to the conductive DC negative rotating plate. The main rotor leads are connected to these conductive plates.(7) Diode flying leads. One diode anode (+) flying lead and another diode cathode (-) flying lead are connected at each of three connection nodes to an exciter armature AC connection lug

The Exciter Rotating Assembly is mounted on the Generator rotor shaft in front of the Generator Rotor Assembly. The assembly consists of a rotor or armature with three phase windings inserted into slots in the armature, a Rotating Rectifier Assembly, and a Ring Resistor.

The armature windings are in line with the exciter stator windings. The three phase leads from the armature windings are connected to a Rotating Rectifier Assembly. The assembly is mounted on the Generator shaft in front of the armature windings.

Rotating Rectifier Assembly

Upper photo - Location of the access opening (arrow) for the generator rotating rectifier assembly on the lower right-hand side of the Generator housing, shown with the cover removed. Lower photo - Rotating Rectifier Assembly

The polarities of the two different diodes that are used in the rotating diode assembly with the red and the black leads.

The Rotating Rectifier Assembly is a full wave bridge rectifier. The assembly consists of six individual diodes and two rotating plates.

Each of the six diodes has a "flying lead" connection and a "base lead" connection. For three of the diodes, the flying lead is the anode (+) connection and the base lead is the cathode (-) connection. The other three diodes have the flying lead as the cathode (-) connection and the base lead as the anode (+) connection. The six diode base leads are connected to either the DC negative rotating plate or the DC positive rotating plate.

The Ring Resistor is connected between the DC positive plate and the DC negative plate. The resistor is in place to protect the diodes from voltage spikes in the main rotor.

The diodes can be tested for proper operation and are serviceable. A failure of one or more of the rectifier diodes could cause the Generator output to be low or erratic. If a problem is suspected with the operation of the rotating rectifier, refer to the Testing and Adjusting, "Rotating Rectifier - Test" section in this manual in order to test the operation of the diodes.

See You Soon!!!

MARYGAR

795F AC Off-Highway Truck Electric: Electric Power Generation : Generator 2012-12-01T07:51:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown