Technical data
8LVA user's manual V1.0
19
Term
Symbol
Unit
Description
Peak current
I
max
A
The peak current is the RMS value of the phase current (current in the motor supply line) for
generating the peak torque. This is only permitted to be drawn for a short time. The peak current
is determined by the magnetic circuit. Exceeding this value for a short time can cause irreversible
demagnetization of the magnet material.
Max. angular acceleration
a
rad/s²
Maximum acceleration of the motor without a load or brake. Value for the dynamics of the motor
(corresponds to Mmax/J).
Maximum speed
n
max
rpm
Maximum motor speed. This is a mechanical condition (centrifugal force, bearing wear).
Average speed
n
Avg
rpm
Average speed for one cycle
Torque constant
K
t
Nm/A
The torque constant determines the torque generated by the motor with 1 A RMS phase current.
This value applies at a motor temperature of 20°C. If the temperature increases, the torque con-
stant is reduced (typically down to 10%). If the current increases, the torque constant is reduced
(typically starting at twice the value of the nominal current).
Voltage constant
K
E
V/1000 rpm
The voltage constant specifies the RMS value (phase-phase) of the reverse voltage induced by
the motor at a speed of 1000 rpm (EMF). This value applies at a motor temperature of 20°C.
When the temperature increases, the voltage constant is reduced (usually down to 5%). If the
current increases, the voltage constant is reduced (typically starting at twice the value of the
nominal current).
Stator resistance
R
2ph
Ohm
Resistance measured in ohms between two motor connections (phase-phase) at 20°C winding
temperature. On B&R motors, the windings use a star connection.
Stator inductance
L
2ph
mH
Winding inductance measured between two motor connections. Stator inductance depends on
the rotor position.
Electrical time constant
t
el
ms
Corresponds to 1/5 of the time needed for the stator current to stabilize in constant operating
conditions.
Thermal time constant
t
therm
min.
Corresponds to 1/5 of the time needed for the motor temperature to stabilize in constant operating
conditions.
Moment of inertia
J
kgcm²
Moment of inertia for a motor without holding brake
Ground
m
kg
Mass of motor without holding brake
2.5.2 Power dissipation
Power from the motors is dissipated via the motor flange and surface of the motor. The following factors are
important to ensure optimal heat dissipation:
•
Thermally open installation
•
Free convection
The motor data specified for the nominal operating point apply to a motor installed in a thermally open system. The
dimensions of the flange plates used for measurement can be found in the following table.
Generally speaking: the larger the flange, the better the heat dissipation.
Size
Dimensions [mm]
Material
8LVx1, 8LVx2, 8LVx3
250x250x6
Aluminum
