What Are Electrical Faults of Leroy Somer Alternator AVR R450?

by Generator D. Diesel Generator

In this article, Starlight Power mainly shares the electrical faults of Leroy-Somer Alternator AVR R450 as well as the action.

Fault	Action	Measurements	Check/Cause
No voltage at no load on start-up	Connect a new battery of 4 to 12 V to terminals F- and F+, respecting the polarity, for 2 to 3 seconds	The alternator builds up and its voltage is still correct when the battery is removed	- Lack of residual magnetism
		The alternator builds up but its voltage does not reach the rated value when the battery is removed	- Check the connection of the voltage reference to the AVR - Faulty diodes - Armature short circuit
		The alternator builds up but its voltage disappears when the battery is removed	- Faulty AVR - Field windings disconnected - Revolving field coil open circuit. Check the resistance
Voltage too low	Check the drive speed	Correct speed	- Check the AVR connections and settings (AVR faulty) - Field windings short-circuited - Rotating diodes burnt out - Revolving field coil short-circuited - Check the resistance
Voltage too low	Check the drive speed	Speed too low	Increase the drive speed (Do not touch the AVR voltage pot. (P1) before running at the correct speed)
Voltage too high	Adjust AVR voltage potentiometer	Adjustment ineffective	- Faulty AVR - 1 faulty diode
Voltage oscillations	Adjust AVR stability potentiometer	If no effect: try normal/fast recovery modes	- Check the speed: possibility of cyclic irregularity - Loose connections - Faulty AVR - Speed too low when on load (or U/F knee-point set too high)
Voltage correct at no load and too low when on load (*)	Run at no load and check the voltage between F+ and F- on the AVR	Voltage between F+ and FAREP/PMG < 10 V	- Check the speed (or U/F knee-point set too high)
Voltage correct at no load and too low when on load (*)		Voltage between F+ and FAREP/PMG > 15 V	- Faulty rotating diodes - Short-circuit in the revolving field coil. Check the resistance - Faulty exciter armature
*() Caution:** For single-phase operation, check that the sensing wires coming from the AVR are correctly connected to the operating terminals.
Voltage disappears during operation (**)	Check the AVR, the surge suppressor, the rotating diodes, and replace any defective components	The voltage does not return to the rated value	- Exciter winding open circuit - Faulty exciter armature - Faulty AVR - Revolving field coil open circuit or short-circuited - Overload (see LED)
() Caution:** Internal protection may be activated (overload, open circuit, short-circuit)

Caution: After operational testing or troubleshooting, replace all access panels or covers.

Leroy-Somer is a leading global supplier of alternators for emergency power. It is divided into two series, one is LSA, another is TAL.

The LSA alternator is designed to be suitable for typical generator applications, such as: backup, marine applications, rental, telecommunications, etc.

It conforms to the main international standards and regulations:

- IEC 60034, NEMA MG 1.32-33, ISO 8528-3, CSA C22.2 n°100-14, UL 1446 (UL 1004 on request), marine regulations, etc.

It can be integrated into a CE marked generator. In addition, Leroy-Somer alternator is designed, manufactured and marketed in an ISO 9001 and ISO 14001 environment.

leroy-Somer new TAL low voltage alternators, with optimal performance for commercial and industrial applications, are a simple, efficient solution for your onsite power requirements. The TAL range complies with international standards and regulations: IEC 60034 and derivative.

Leroy-Somer’s TAL alternator range is designed to meet the specific needs of telecommunications, commercial & industrial markets, as well as stand-by and prime power applications. It is compatible with most engine brands, such as Cummins, Perkins, Volvo, Deutz, Yuchai, Weichai, etc. It can be integrated into a CE market generator set.

Electrical design

Class H insulation

Low voltage winding

6-terminal plate (adapted plate for 6 & 12 wires machine)

Possibility of star and delta connection

Optimized performance

Note: No matter it is LSA or TAL series alternator, it is available to 50 Hz and 60 Hz. Leroy-Somer alternator is not only low voltage alternator, but also medium and high voltage alternator.