Page 222 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

r = Radius of shaft in meters
Then Torque T = F x r (Nm)
Power developed by shaft

Work done = Force x distance
Distance travelled by the shaft in 1 revolution = perimeter = 2 x πxr
Work done by shaft in 1 rev = F x 2 x π x r

N N N
As F x r = T,
60 60 60
Work done = F x2π x r = 2 πΤ
60 60 60
N
Speed = N rpm or rps. Or second for 1 revolution 60 N

60 N N N N N
60 N N N
N N
N
J
60
T π 2 60
J
T π 2 60

N Power developed by shaft in 1 second or Watts

T
J π 2

S
S
60
N 60 60 60 60 60 S 60
N 60 .NT 2π .NT
2π 60
60

.NT
2π N
N N
HP

Horse power developed HP
HP
J

T π 2
60
746
x N
J
T π 2 60 N S N 60 x 746 N 60 x 746
N
S
J
60 N.T T π 2 N.T N N 2π S N.T
J T π 2
2π
S
J J J 60
2π

Torques in dc motors 2π .NT HP π 2 π 2 2π J S T T 60 watts watts J S or watts
or
or

S S S
60
60

60
.NT

746
x
60
HP

.NT
.NT 2π
• Gross torque / armature torque 60 60

2π

60 x 746 2π .N.T 2π HP .N.T

2π .NT HP

2π
.NT
2π
.N.T 746 x
60
746 x
60
HP
• Shaft torque 2π N.T J S or x 60 HP HP 60 x 746 HP
HP
watts
60 x 746 x
60
746 60
N.T

2π
x 746
746

or
N.T 2π
• Lost torque 60 60 J S 2π watts N.T watts wattsor

J
J

N.T or
2π
.N.T
watts
2π

or watts
• Power equation of a shaft 60 2π N.T S 60 J J or S
S S
HP

60

60
.N.T
N.T
x
HP
60 2π 746 2π 2π .N.T N.T watts 2π N.T J or watts
2π J 2π
J .N.T
or

watts

60 x 746 60 2π S S or HP S

60 .N.T .N.T HP
60
2π
HP
HP
• Power equation of a shaft 60 746 x 60 x 60 x 746
60
x 746
746
2π N.T J Eb la 2π .NT a 2π .NT a 2π .NT a
Eb

Eb
watts
Armature torque(ta) / gross torque la 60 la 60
or

60
2π

N.T
S
or
60 J 2π watts N.T
N.T 2π

J
J
60
Power equation of a shaft S Eb Ia N.T 2π N.T 2π 60 J watts wattsor Ia 60
or
60S Eb
Ia
Eb S 60
watts
.NT 60
Ta
J or Ta

Eb la 2π a Ta N 60 2π S S N or watts 2π N
2π60
2π

.NT
Eb la 60 a 2π .NT 2π .NT
a
60
• Power developed in armature 9.55 Eb 2π a 60 Eb Ia
Ia .NT .NT
la Eb

la
Eb
Ia

Eb

9.55
a a 9.55
2π
Eb

Ia
m
N

Ta Eb Ia 60 Eb la Eb la N 60 60 m N N m
N
60
60
N
Armature Torque Ta 2π N Eb Ia 60 Ia Eb 60

N
Ta
.NT Ia 60Ia
CITS : Power - Electrician & Wireman - Lesson 1 9.55 Eb 2π 2π .NT 2π Eb 60 2π .NT
Ta
Eb

Ta
BHP N 2π
Ia
m
9.55 Eb Ia N Ta 60x746 N 2π N 2π BHP N 2π 60x746 BHP
60x746
N N m 9.55 Eb Ia
Ia
Eb
9.55

N 2π 9.55 N m
Ia Ia m
.NTsh Eb Eb
9.55
.NTsh
N
2π .NT BHP N 2π N mN 2π .NTsh
BHP
2π .NT BHP 60 x N N N BHP m 60 x 746
746
60
746
x
60x746 BHP .NT 2π .NT
2π
x .NT .NT BHP BHP
60x746 2π 60 x 746 209

BHP 2π
x
BHP
x
2π Tsh 60x746 60x746 60 746 x BHP 60 x 746
.NTsh
BHP
BHP 2π Tsh 2π N BHP Tsh 2π N
60x746
60x746
2π
.NTsh
N

BHP 60 x 746 CITS : Power - Electrician & Wireman - Lesson 30-37
.NTsh .NT 2π

2π
sh
746
60 x BHP BHP
2π
.NTsh
60
x
BHP x 60 x BHP 2π .NTsh 746
746 746 x 60
BHP
Tsh BHP x 60 x 746 60 x 746
60 x
746

Tsh 2π N BHP x 60 BHP 746 x 60 x 746
x
Tsh N 2π Tsh x 60 x 746
60 x
BHP x P
BH
746
Tsh
Tsh 2π N 2π N
2π N N
2π