A. Click on generatormodelcodes for a matrix of generator model codes to determine the generator type, frame size, number of bearings, voltage range, and special engine adaptions.

A. A synchronous AC generator (alternator) is an alternating current generator whose rotating speed is directly proportional to the frequency of the AC voltage wave it produces. All Marathon MAGNAPOWER®, MAGNAMAXDVR®, MAGNAPLUS®, PANCAKE®, and LIMA®MAC generators are synchronous generators.

A. An Induction (asynchronous) generator is an AC generator (alternator) whose rotating speed is not directly proportional to the system frequency. An induction generator is basically an induction motor tied to, operating in parallel with, another source of electrical power - usually the public utility - whose shaft is caused to turn faster than the synchronous speed (frequency) of this other power source. Under this condition, the induction generator delivers power back onto the power source. Marathon's PRIMELINE® generators are induction (asynchronous) AC generators.

A. Click on PMG for an article discussing the advantages of a PMG Excitation Support System.

A1. If the generator is either a Lima Electric Co type LIMA®MAC or Type SER, or a Marathon Electric type MAGNAPLUS, check the generator nameplate for an engine adaption kit (ADPT KIT) part number and/or generator serial number. If a Marathon Electric type MAGNAMAX check the nameplate for a model number and/or serial number. Contact the factory with these numbers for information as to what engine adaption was installed when the unit shipped from the factory.

A2. If none of the above information is available, or if the generator is of another make or model, click on generator adaption for information regarding taking measurements to determine the existing generator's SAE drive disc size, and SAE flywheel housing size.

A. Click on engine adaption for information regarding taking measurements of the engine to determine the SAE flywheel, and flywheel housing installed on the engine.

A. Click on Rating Adjustment Nomograph. Reduce the generator's nameplate kVA rating by the de-rating factor determined by applying the site altitude and ambient temperature to the nomograph. (See the example outlined in blue.)

A. Yes with certain limitations. Click on Hazardous Locations for an article discussing the suitability of Marathon Electric generators for installation in Hazardous Locations.

A. The term time constant refers to the length of time required to change from one condition to another. Usually considered to be the time required to complete 63.3% of the total rise or decay of voltage and/or current flow following the addition or rejection of electrical load.

A. This value determines the current flowing during the period when the subtransient reactance is the controlling value.

A. The apparent reactance of the stator (main armature) winding at the instant a short circuit (fault) occurs. This reactance is used for the calculation if the initial maximum symmetrical and asymmetrical fault current.

A. Click on Add-On PMG Specs for these specifications.

A. Storage and operating temperature ranges of Marathon generators will vary depending upon the model of automatic voltage regulator being used. The storage and operating temperature ranges for the standard AVRs used with Marathon generators are:

1. Marathon Electric Model SE350 automatic voltage regulator storage temperatures, are (-) 65°C to (+) 85°C, and operating temperatures are (-) 40°C to (+) 60°C.
2. Marathon Electric Model PM300 automatic voltage regulator storage temperatures, are (-) 65°C to (+) 85°C, and operating temperatures are (-) 40°C to (+) 60°C.
3. Marathon Electric Model DVR2000E/EC automatic voltage regulator storage temperatures are (-) 40°C to (+) 80°C, and operating temperatures are (-) 40°C to (+) 70°C.
4. Basler Electric Model AVC63-12B2 automatic voltage regulator (used with our 400 Hertz generators) storage temperatures are (-) 40°C to (+) 80°C, and operating temperatures are (-) 40°C to (+) 70°C.

Should the voltage regulator being used be other that those listed above, please consult with the factory for these temperature ranges.

A. Bearing life us usually expressed as the number of hours an individual bearing will operate before the first evidence of metal fatigue develops. B10, or L10 are terms used when referring to bearing life. Click on Bearing Life for a discussion of these terms.