Operation on foreign converters
8.6 Operation on foreign con-
verters
Principally, operating MS2N motors on foreign
converters is possible. In the following, the
designs and possible adjustment ranges are rep-
resented.
WARNING
Danger of explosion or material damage due to
overload!
Observe the following requirements for safe
motor operation on foreign converters. Connec-
tion of all necessary sensors and additional
devices for a safe operation and their evaluation
lies in the sole responsibility of the plant manu-
facturer or operator.
Requirements on the power output stage
•
Converter with pulse width modulation
• Pulse frequency 4 kHz …16 kHz
Voltage load of the motor
During converter operation, the motor underlies
a higher voltage load (insulation system, bearing)
than on a sinusoidal source voltage only.
Standard values for peak voltage and rate of rise
of voltage:
•
Peak voltage U
pk
on motor clamps ≤ 1.56 kV
•
Rate of rise of voltage du/dt ≤ 5 kV/μs
Maximum allowed limit load:
In the case of critical rate of rise of off-state
voltage du/dt ≥ 5 kV/µs, the limit values (peak
voltage, voltage rise time) according to limit
curves A according to DIN VDE 0530-25 (VDE
0530-25):2009-08 (Figure 14 Limit curve A)
must be kept. Therefore, observe the limit values
for voltage rise time and critical rate of rise of
off-state voltage.
Limit values for voltage rise time and critical rate
of rise of off-state voltage:
• Voltage rise time > 0.17 µs
•
Rate of rise of off-state voltage du/dt < 8
kV/µs
Monitoring functions
• Speed monitoring of maximum permissible
speed
• The motor load must not exceed the allowed
continuous operation characteristic curve.
The converter setting data for controlling and
monitoring must comply with the type code
data.
• Temperature control to protect from thermal
overload
– The temperature sensor of the motor
winding must be connected and evalu-
ated on the converter (ensure monitoring
function, observe polarity of tempera-
ture sensor, limit switch-off temperature
according to ⮫ Chapter 5.2.3 “Thermal
motor protection ” on page 18).
–
Temperature model or I
2
t-monitoring
within converter. Due to the coupling
time of the temperature sensor, an addi-
tional suitable temperature model or an
I
2
t-monitoring must be used.
Requirements for motor operation with holding
brake
•
Ensure the brake functionality during normal
operation due to voltage control, current
monitoring, cyclic control of the brake
holding torque, for example.
• Provide an external or an integrated protec-
tive circuit within the foreign converter to
switch the holding brake (inductive load).
• Never use the holding brake of the motor as
an operating brake.
•
Idle time after an emergency stop before
restarting ≥ 3 minutes.
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