SIEMENS
8/8
Siemens MD 50.8 · 2017
Appendix
Lists
List of variables to dimension the drive
8
■
Important drive technology variables
*
The numerical value of a variable in previously used units multiplied by the conversion rate gives the numerical value of the variable in SI units.
Conversion from kW to hp:
1 kW = 1.34102 hp
1 hp = 0.745700 kW
1 hp = 1.01387 PS
hp = horse power (US)
PS = Pferdestärke (horse power in German)
SI unit
Size
Symbol
Unit symbol
Designation or
conversion factor
*
SI
Previously
SI
Previously
Length (distance)
l
L, s
m
m
1 km = 1 000 m
Area
A
F
m
2
m
2
1 m
2
= 100 dm
2
Volume
V
V
m
3
m
3
1 m
3
= 1 000 dm
3
1 dm
3
= 1 l
Plane angle
rad
Degrees °
1 rad = 1 m/m
1 L =
/2 rad
1
/180 rad
Rotation angle
Degrees °
1’ = 1°/60; 1’’ = 1’/60
Time
1 min = 60 s
1 h = 60 min
Time period/duration
t
t
s
s
1 d = 24 h
Frequency
f
f
Hz
1/s
1 Hz = 1/s
Speed
n
n
rpm
rpm
Rotations per minute
Velocity
v
v
m/s
m/s
1 km/h =
Acceleration
Acceleration due to gravity
a
g
b
g
m/s
2
m/s
2
g = 9.81 m/s
2
Angular velocity
rad/s
1/s
Angular acceleration
rad/s
2
1/s
2
Mass
m
m
kg
kg
1
Density
d
kg/dm
3
kg/dm
3
10
3
Force
Force due to weight
F
G
P, K
G
N
kp
9.81
1 N = 1 kg · 1 m/s
2
Pressure
Mechanical tension
p
p
Pa
N/m
2
N/mm
2
kp/cm
2
kp/mm
2
1 Pa = 1 N/m
2
9.81 · 10
4
9.81
Work
Energy
Quantity of heat
W
W
Q
A
E
Q
J
kpm
kcal
9.81
4187
1 J = 1 Nm = 1 Ws
Torque of a force
Torque
Bending torque
T
M
t
M
d
M
b
Nm
kpm
9.81
1 Nm = 1 J
Power
P
N
W
PS
735.5
1 W = 1 J/s = 1 Nm/s =
Moment of inertia
J
kgm
2
kpm
2
9.81
1
3.6
m/s
kgm
²
s³
© Siemens AG 2017