In the lower speed region load is large ...so current will be large thus E will reduce as we also reduce field flux by increang Rf but we observed that the rate of decrease in current is around 50 times the reduction in flux hence speed reduces
When the induced torque is greater than the load torque the motor will accelerate...And then it will settle down...U should always think about induced torque with respect to load torque....
if we are changing the voltage across armature only and not the field, the terminal voltage has to remain Vt itself. While drawing the graph, in the expression relating w and Tind, Vt is taken as armature voltage. Why is that so? Isn't that quantity still representing the terminal voltage of the machine?
In my video safe working limits I have explained that armature voltage control should be used to control speed below base speed, which means only voltage should be reduced...yes you are correct that insulation might get damaged over time, that is why this method is used for speed control for below base speed...I hope it is clear....
Sir, I think I have some problems with the loop equations. 1) If Va increase, why not back emf increase too? 2) U said VT and Va increase linearly. So for Va to increase, VT will increase, so flux should increase. I hope you can help. I have some wrong directions with my thinking. Thank you
Sir u didnt tell why the speed of the motor reduces with increase in resistance at lower speed operation in the last video as well as this ?? i m unable to get it
+vikash tiwari if ur telling about the issue in field resistance control..In the field resistance control i have told in the ending part of the lectures that why u should not control low speeds using field resistance control...Thanks...
Rf☝w👇 in case of lower speed I'm nt sure 100% but i think... Ia☝coz 👇Ea nt enough to compensate 👇@ ...@👇 greater than Ia☝ exactly opposite upper speed case
Sir agar aap na hote to mai na jane kya kar leta , meri back confirm thi par ab sb samajh me aa gaya
Thank you so much sir 😀👍
In the lower speed region load is large ...so current will be large thus E will reduce as we also reduce field flux by increang Rf but we observed that the rate of decrease in current is around 50 times the reduction in flux hence speed reduces
rate of decrease in current? ? How current decrease wen load increase??
At lower speed if field resistance increases field current decreases then field flux reduces hence speed increases sir
when torque induced increses the speed should be decreased ur saying speed is increasing can explain me sir
When the induced torque is greater than the load torque the motor will accelerate...And then it will settle down...U should always think about induced torque with respect to load torque....
if we are changing the voltage across armature only and not the field, the terminal voltage has to remain Vt itself. While drawing the graph, in the expression relating w and Tind, Vt is taken as armature voltage. Why is that so? Isn't that quantity still representing the terminal voltage of the machine?
Vt=k*Va so only the graph is compressed or expanded but the shape is the same
Sir after speed is achieved .again torque is decreased...speed will also decrease na sir....???.plz explain.
As u told for the same load.. If I increase the voltage I can get the higher speed.. Is it possible in the point of insulation view.. Xplain sir..
In my video safe working limits I have explained that armature voltage control should be used to control speed below base speed, which means only voltage should be reduced...yes you are correct that insulation might get damaged over time, that is why this method is used for speed control for below base speed...I hope it is clear....
Sir if Va changes Vt also changes so phi should be change .
Please sir reply
Sir, I think I have some problems with the loop equations.
1) If Va increase, why not back emf increase too?
2) U said VT and Va increase linearly. So for Va to increase, VT will increase, so flux should increase.
I hope you can help. I have some wrong directions with my thinking.
Thank you
sir is there any other method (other than the graph) to explain why field resistance control shouldnot be used at lower speeds
Well, it is these graphs and other mathematical tools that help us to understand the machine better....
Sir u didnt tell why the speed of the motor reduces with increase in resistance at lower speed operation in the last video as well as this ?? i m unable to get it
+vikash tiwari if ur telling about the issue in field resistance control..In the field resistance control i have told in the ending part of the lectures that why u should not control low speeds using field resistance control...Thanks...
Sir why Va will not affect field ?Va is also across the filed only
No it will not because between va and field there is va convereter
Rf☝w👇 in case of lower speed I'm nt sure 100% but i think... Ia☝coz 👇Ea nt enough to compensate 👇@ ...@👇 greater than Ia☝ exactly opposite upper speed case
noob