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DYNAMIC BRAKE

By

S.K.Sinha

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Dynamic BrakeBy means of the Dynamic Brake System, the kinetic energy of the loco & train is

converted into other forms of energies as quickly as possible to stall the loco.

Kinetic

energy of the

Loco /Trains

electric

energy (IRt)

heat energy ( JH) for dissipating of

heat into grids fitted in the Nose

Mechanical energy (I/2)

for blowing up and

cooling down the

dissipated heat of the grids.**As the energy transformation is

not possible at zero speed by above method in DC/AC-DC

TRANSMISSION , the dynamic brake system can not work at zero speed.So this is used as auxiliary brake to the main brake to make the loco slow.

Friction Loss1

2

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What is Dynamic Brake?

cont..

SwitchingOp

erationdurin

gDyna

micBrakeO p

eratio

n

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Effects of Dynamic Brake at

different speeds--- Around zero speed the braking Torque remains almost

zero.

At the speed up to 35-40 KMPH, T Brake N

This is because the excitation system of the locomotive

is designed such that the M/Gen. current remainsconstant and hence the field strength of theTMs(Converted to Gen.)also remains constant .

And above 35-40 KMPH, T Brake 1/N

As the field strength is made reduced successively byreducing M/Gen current such that.

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Changes occurred in Circuits

during Dynamic Braking(1)(1)BKT(Braking Switch) comes into Braking Mode which

brought-----

(a) all TMs fields in series. (PCs P1,S1 & P32 operate)

(b) Above series across M/Gen.

(c) TMs armatures across Braking grids and Blower motors.(PCs P21, P31 operate in single BKT design andP21,P31 ,S21and S31 operate in Double BKT design )

Hence PCs P1,P21.P31,P32 & S1 operate when there are single

BKT and single Reverser.S21 and S31 also operatewith double BKT and double Reverser.

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Changes occurred in Circuits

during Dynamic Braking(2)2.Energises B K R s which

(a) Make engine speed of 4th notch.(ESR1,and 3or A &C solenoid Valves)

(b)Replace engine speed signal with brakingcontrol signal at Mixer Ref circuit.

3.Set up BKCP for increasing or decreasing ofthe ref. signal at mixer circuit.

(M/Gen. Voltage becomes1.6 V to 30V)

4.If the M/gen is DC type, this is converted intoDifferential Compd. generator for morestability

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Changes occurred in Circuits

during Dynamic Braking(2)

[For driving FTTM & RTTM blowers and

M/Gen (or Alternator) during Dyn. brake

operation the engine speed becomes

equivalent to 4th speed even at IDLEthrottle position. ]

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Braking Control

Potentiometer

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Max. B

ref. limit

Min.. B

ref. limit

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Auxiliaries of Dynamic Braking

System -----

1.Resistor Cooling- Blower Motor

2.Traction Motor Cooling System-FTTM &RTTM Blowers connected which rotate

proportional to Engine speed.

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Advantage of installation of Dynamic

Brake System in a loco

The main advantage is that the loco can beslowed down very smoothly and easily.And,consequently the loco can be :-

1.controlled over easily either on grades orlevels with minimum jerks.

2 stopped smoothly and with minimum wearson wheels and brake shoes when other

braking system is being applied to stop theloco.

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ThankY

ou