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Step Up Chopper

This instruction manual outlines the operation and study of the SCR Step-Up Chopper model SD-409, detailing objectives such as observing output voltage changes in relation to SCR triggering and duty cycle. It explains the theory behind the chopper's functionality, including energy transfer during the ON and OFF periods of the SCR. The procedure includes connecting instruments, measuring times, and calculating output voltage based on the observed data.

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44 views3 pages

Step Up Chopper

This instruction manual outlines the operation and study of the SCR Step-Up Chopper model SD-409, detailing objectives such as observing output voltage changes in relation to SCR triggering and duty cycle. It explains the theory behind the chopper's functionality, including energy transfer during the ON and OFF periods of the SCR. The procedure includes connecting instruments, measuring times, and calculating output voltage based on the observed data.

Uploaded by

Ushà Nítwál
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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ISO-9001: 2016Co.

SINCSM
INSTRUCTION MANUAL
SCR STEPUP CHOPPER.
Model :-SD-409

Objective9

1 To Study the operation of SCR Slep-UP Chopper.


2 ToStudy the triggering cireuit used for SCR Step-UP Chopper.
3 ToObserve &Note the DC O/P Voltagew.r.t. ToN &TOFF of SCR. Compare
the theoretical & practical values.
4 To Observe &Note change in DCVoltage w.r.t. changes in duty cycle of
triggering circuit.
Instruments Required :
CRO, Voltmeter (0-30V).
Theory -
Step Up chopper gives the minimun output voltage equal to the input
voltage and it increases by changing the duty cycle of applied signal.
When SCR is conducting the appeared voltage. Vde generates current I
through SCR and simultarneously energy is stored in the inductor L.. Now when
SCR isswitched OFF point Abecomes positive
With respect to point B due to inductor L, diode D, Forward biased and the
stored energy in induckor I. is transferred to the capacitor through diode Dand the
capacitor Cstarts charging.
B
(O00001

Vde

SindhU ELECTRONICS &COMMUNICATIONS PVT. LTD.


ISO 9001:2008 Co. SINCSM
Cgets fully charged to the potential at point B, the potential at point Bwill
be more than that of point A. So diode D becones reverse biased and blocks the
charge at capacitor this capacitor is charged at a higher voltage than the input
supply so the output voltage Vo will be more than the input voltage Vd.c.
Energy stored in L during ON period of SCR.
=Vd.c. L Ton. --(1)
Energy transferred to cap C, during OFF period of SCR.
=(Vo- Vd.c.). I.Toff --.2)
as Energy stored= energy transferred.
So eq (1) eqn = (2)
i.e. Vd.c. I. Ton= (Vo - Vd.c.) . I.Toff.
Vo= Vde (Tont+Toff --(3)
Toff

From(3) Vo will be depends on ON & OFF time of SCR.


Procedure :
(1) Study the CKT given on the front panel of the kit.
(2) Connect voltmeter at the O/ P and C.R.O. at the anode of Diode to see the
Chopped O/P.
(3) Switch ON the power supply.
(4) Keep pot P, at minimum and measure the T on &T off time of trigger pulse.
(5) Calculate the Vo using eqn (3)
(6) Now vary the duty cycle by changing the position of P: and observe the
change in Votake down readings according to observation table.

SindhUELECTRONICS &COMMUNICATIONS PVT. LTD.


ISO-9001: 2015Co.
SINCSM
Observation Table :
Sr. Ton Toff Ton+Toff Vdc Vo
Vo= Vdc ron+Toff
ms Toff volts Toff measured
No. Ims

volts.

Result :
The Step up chopper will increase the I/P voltage the minimum and maximum
output voltage are found to be =Vo minimum = Vo maximum=

SIndhU ELECTRONICs &COMMUNICATIONS PVT. LTD.

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