Sm 1Xx Voltage Protection Module - HEIDENHAIN TNC 410 M Technical Manual

2.5.7 SM 1xx Voltage Protection Module

April 2007
If synchronous motors or direct drives, such as synchronous spindles or
torque motors, are operated in the field weakening range (for example, as
spindle drives), a power interruption (e.g. power failure) can result in a
voltage increase at the power connections of the motor. The voltage
increase can damage the inverters and the motor. To prevent this, a voltage
protection module must be inserted in the motor lead between the motor
and the inverter. If an error occurs, the SM 1xx will short-circuit the motor
phases. The released braking energy is converted into heat.
The following formula can be used to decide whether an SM 1xx voltage
protection module must be used:
·
850 V
N =
max
·
U0
The result N means: If the motor is operated at a speed greater than
max
speed N a voltage protection module must be used.
max,
The short-circuit current of the motor (given in the motor data) is decisive for
the selection of the SM 1xx voltage protection module.
The maximum short-circuit current I
to the following formula and must be less than the maximum phase current
of the SM 1xx:
U0
I =
K
·
3
XL
Where: XL = Xstr1 + XH
When Xstr1 = 0, then XL = XH.
Choosing between SM 110 and SM 130:
When I < 63 A, then SM 110.
K
When 63 A < I
The following data can be found in the motor table of the control:
U0: No-load voltage [V],
Xstr1: Stator leakage reactance [Ω] ,
Inductive reactance [Ω] , (Note: In the motor table the value is
XL:
expressed in [mΩ]),
XH: Magnetizing reactance [Ω]
expressed in [mΩ]).
(Note: The data is not always expressed in the basic unit in the motor table.
In the above-mentioned formula, however, you must enter the data in the
basic unit of measure.)
Accessories for Compact Inverters and Modular Inverters
N
noml
2
of a motor can be calculated according
K
< 300 A, then SM 130.
K
(Note: In the motor table the value is
2 – 89