FS Class E656

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FS class E656

Unit E656.476 in XMPR livery.
Power type	Electric
Builder	Officine Casaralta, Officine Reggiane, SOFER, TIBB componentistica Ercole Marelli, Ansaldo, Asgen, Italtrafo
Build date	1975-1989
UIC classification	Bo'Bo'Bo'
Wheel diameter	1.250 m
Length	18.290 m
Width	3.000 m
Height	3.800 m
Locomotive weight	120 tons
Electric system(s)	3,000 V DC
Traction motors	DC
Top speed	150 km/h
Power output	continuous: 4,800 kW - hourly: 4200 kW
Tractive effort	249;kN
Safety systems	RSC4; SCMT
Career	FS Trenitalia
Number in class	459
Nicknames	"Caimano" (Caiman)
Disposition	In service

FS class E655

E.655.505 in Terni in its original livery, July 2nd 2006
Power type	Electric
UIC classification	Bo'Bo'Bo'
Electric system(s)	3,000 V DC
Traction motors	DC
Top speed	120 km/h
Tractive effort	300 kN
Career	FS Trenitalia
Disposition	In service

This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (January 2008)

The Class E656 is an italian articulated rheostatic-type electric locomotive built from 1973 to 1989. They are all-purpose lomotives, and have been used on every kind of train, ranging from freight to intercity ones, and represent the evolution of the 646/5 class.

[edit] Technique

The hull is divided in two parts, each one with its own two axles bogie, plus a central bogie in the middle. Each boogie mounts 4 DC motors, each providing 400 kW, for a total of 12. Intitial project speed was 160 km/h but was reduced to 150 due to stability problems; also, the heavy mass of the loco did not allow the use of rheostatic braking. Recently many E656s have been transferred to the Cargo Division of Trenitalia, to haul freight trains. The gear ratio has been reduced from 28/61 to 23/66, and the speed limit to 120 km/h. The modified units form the E655 class.

[edit] Series

The 656 class is officially subdivided by FS in three series:

• 1st series (001 - 307)
• 2nd series (401 - 550)
• 3rd series (553 - 608)

The differences between series regard electrical and mechanical equipment. Plus, sixth series locos have four field weakening shunts in parallel and super - parallel motor combinations (other series have three), and the 78-wire cable to remote control the loco from a control car (Carrozza Semipilota) or another Delfina-fitted locomotive.

However, railfans tend to split them in six series, wich considers other particulars:

[edit] Motors & Electrical description

The locomotive has 12 82/400 motors, with class B insulation, 4 per bogie.

They can be connected in the same combinations used on E646-5:

• Series: all motors are connected in series, five shunts;
• Series-Parallel: two branches of six motors each, five shunts;
• Parallel: three branches of four motors each, three shunts (four on 6th series);
• SuperParallel: four branches of three motors each, three shunts (four on 6th series);

Like their predecessors, E656 have a rheostat (31 resistors subdivided in 21 packs, for a total resistance of 17.015 ohm) that, by varying its resistance, gradually regulates the flow of current to the motors on starts, and on each time a transition to the next combination is made; however, unlike them, rheostatic exclusion is not commanded manually, by default.

Driver console of an E656; the lever in the middle is the combination selector.

The driver selects the desired combination, and this job is automatically accomplished by an automatic system, which, through a particular array of logic gates and other components (capacitors, resistors, etc.), called "RAE" (Relè Accelerazione Elettronico), commands a rotating device (called "avviatore automatico"). The driver selects the maximum exclusion current through a potentiometer on his desk, and the system, when the c.e.m.f. present in the motors brings the current (which is readed by transducers) to a value lower than the set current, makes the avviatore advance, closing the rheostat contactors (thus shunting the relative resistors) as speed builds up, until it is totally excluded; similarly it may go backward, when the current reaches high levels in respect of speed.

The different types of connections of the motors in the various combinations is accomplished by closing various contactors; their set-ups during transitions are handled by a device called CEM ("Commutatore Escluditore Motori").

If rheostatic exclusion is needed to be commanded finely (i.e. on coupling maneuvers, or in case of heavy train and/or poor adherence situations), the driver can use the PAC (Pomello Avanzamento Comandato), a small lever that makes the "avviatore automatico" advance or go backwards position by position (for Series combination only).

On Third series locomotives (official classification), many functions such as the ones of RAE, Avviatore Automatico, CEM, etc., are assumed by an electronic control unit, similar to the ones employed on FS Class E444.

It is important to exclude the rheostat as fast as possible: the rheostat is robust and dimensioned to stand high currents, however it cannot stand them for an excessive period of time, as there is the risk to melt it; the driver has to keep this in mind, when driving; when temperature is too high (> 200 C°), the "Vr" (Ventilazione Reostato, Rheostat Fans) light starts to blink on the driver's consolle, in order to warn him.

[edit] Auxiliary Systems

The following components form the auxiliary systems:

• two W242 compressors used for air production;
• an asyncrhronous 17 kW three-phase motor, that is used to activate the 4 groups of motor-cooling fans, 7 groups for rheostat cooling and 2 fans for cabin air conditioning;
• an 3 kVA transformer used to recharge the 24 V batteries, plus other 4 for cabin heating and another one for glass defrosters.

They are feed in various ways, depending on the series:

• on 1st and 3rd series by 2 125 kVA motoalternators, activated by a double-collector 95 kW 3000 V motor;
• on 2nd and 4th series by a single 3000 V DC/450 V AC - 60Hz 180 kVA static converter;
• on 5th and 6th series two 3000 V DC/450 V AC - 60Hz 120kVA static converters.

Motor cooling fans are automatically activated when the reverser is in non-neutral position, while rheostat fans when the temperature into the rheostat's resistors reaches 65 °C or are manually activated by the driver via an apposite botton.

[edit] Significant units

• Unit 200 had been fitted with 2 ARSA static convertes for testing purposes.
• Units 458 and 468 mount digital Octopus control units, which allow remote command of two or more locomotive from a single driving cabin. These units also have four weakenig field shunts in Parallel and SuperParallel combinations as sixth series' units.

[edit] See also

• FS Class E646/5
• FS Class E636