2 Engineering
2.9 Three-phase motors
DB1 variable frequency drive
11/20 MN040031EN
Eaton.com
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2.9 Three-phase motors
DB1 variable frequency drives can be used to drive the following three-phase
AC motors with sensorless control:
•
Three-phase asynchronous motor (DAM),
•
Permanent magnet motor (PM),
•
Brushless DC motors (BLDC),
•
Synchronous reluctance motor (SynRM).
When delivered, the DB1 variable frequency drive is set with U/f modulation
for the assigned motor output of a three-phase asynchronous motor.
2.9.1 Motor selection
Configurations such as the ones used in outrunner motors and slip-ring
motors also fall under the three-phase asynchronous motor category (which
in turn is also referred to as the “squirrel-cage rotor” or “standard motor”
category). These motors can also be run with DB1 variable frequency drives,
but will normally require additional engineering, modifying the various para-
meters, and detailed information from the motor manufacturer.
General recommendations for motor selection:
•
Only use motors that have insulation class F (maximum steady state
temperature of 155 °C ) at least.
•
Choose 4-pole motors where possible
(With synchronous speeds of: 1500 min
-1
at 50 Hz or 1800 min
-1
at
60 Hz).
•
Take the operating conditions into account for S1 operation
(IEC 60034-1).
•
Do not oversize the motor, i.e., the motor should not be more than one
rating level higher than the assigned motor output.
•
In the case of undersized motors, the motor output for continuous ope-
ration should not be more than one rating level lower than the rated
rating level (in order to ensure that the motor will be protected).
•
When running tests or commissioning a system with significantly lower
motor outputs, the motor’s rated operational current must be adjusted
using parameter P-08 (“rated motor current”).
￫
Vector mode, as well as running PM, BLDC, or SyncRM motors,
will need for parameters P-60 and P-61 on DB1 variable fre-
quency drives to be configured accordingly.
￫
Check whether your chosen DB1 variable frequency drive, in
terms of its cooling, is compatible with the assigned three-
phase AC motor in terms of voltage (mains and motor voltage)
and the rated current.