In this chapter we are going to study about the types of Dynamic Braking i.e DC and Zero Sequence Braking.In the earlier lecture we have studied of the two types of Dynamic Braking that is AC Dynamic Braking and Self Excited Capacitor Braking,in this lecture we will study about the rest of the two dynamic braking named in the heading.
इसी टॉपिक को हिंदी में पढ़ने के लिए यहां क्लिक करे:-https://electricalvideolibrary.blogspot.com/2018/11/dc-and-zero-sequence-dynamic.html
Lets Start with...
3.DC Dynamic Braking:
In DC Dynamic Braking there are two type of connection similar to the AC Dynamic Braking ie-
1)TWO LEAD CONNECTION :-In two lead connection we remove the three phase supply from the motor and connect the any two phase with the DC supply Voltage as shown in figure 1.
2)THREE LEAD CONNECTION:-Three lead connection is similar to the two lead connection but the only difference is that the remaining phase in two lead connection is also connected with the anyone phase the two dc connected phase as shown in figure 1.
WORKING:-
We know there is rotating magnetic field is generated in the air gap by the stator in 3 phase induction motor and rotor start rotating in process to catch up that field so that it can reduce the flux linkage through it.Its the statement of the lenz law it opposes the cause.In our case if we create the stationary magnetic field by replacing the three phase supply with the DC supply for braking.Here rotating magnetic field suddenly change in to the stationary field but the rotor will be rotating because of the inertia and now the flux will link with the rotor because of the stationary field now in accordance with the lenz law it will try to catch the stationary field it means for doing so it has to stop.
In zero sequence breaking we connect all the winding in series and finally we connect it with either AC or DC supply as shown in figure 2.
इसी टॉपिक को हिंदी में पढ़ने के लिए यहां क्लिक करे:-https://electricalvideolibrary.blogspot.com/2018/11/dc-and-zero-sequence-dynamic.html
Lets Start with...
3.DC Dynamic Braking:
In DC Dynamic Braking there are two type of connection similar to the AC Dynamic Braking ie-
1)TWO LEAD CONNECTION :-In two lead connection we remove the three phase supply from the motor and connect the any two phase with the DC supply Voltage as shown in figure 1.
2)THREE LEAD CONNECTION:-Three lead connection is similar to the two lead connection but the only difference is that the remaining phase in two lead connection is also connected with the anyone phase the two dc connected phase as shown in figure 1.
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| Figure 1.Two lead,Three lead Connection |
We know there is rotating magnetic field is generated in the air gap by the stator in 3 phase induction motor and rotor start rotating in process to catch up that field so that it can reduce the flux linkage through it.Its the statement of the lenz law it opposes the cause.In our case if we create the stationary magnetic field by replacing the three phase supply with the DC supply for braking.Here rotating magnetic field suddenly change in to the stationary field but the rotor will be rotating because of the inertia and now the flux will link with the rotor because of the stationary field now in accordance with the lenz law it will try to catch the stationary field it means for doing so it has to stop.
4.ZERO SEQUENCE BRAKING:
In zero sequence breaking we connect all the winding in series and finally we connect it with either AC or DC supply as shown in figure 2.
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| Figure 2.Zero Sequence Braking |
WORKING:-
Working of the zero sequence braking is similar to the DC sequence braking.When we apply the AC source then the rotor will chase the pulsating magnetic field and stop.When we apply the DC source its working is similar to the DC sequence braking.When we apply AC source then we can break it upto the one third of the maximum speed while with DC source we can get the whole range of braking.
Working of the zero sequence braking is similar to the DC sequence braking.When we apply the AC source then the rotor will chase the pulsating magnetic field and stop.When we apply the DC source its working is similar to the DC sequence braking.When we apply AC source then we can break it upto the one third of the maximum speed while with DC source we can get the whole range of braking.
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