ABB ACS800-37-0170-3 - Protecting the motor insulation and bearings

Planning the electrical installation
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3. Check that the motor voltage rating meets the application requirements:
See notes 6 and 7 below the Requirements table.
4. Consult the motor manufacturer before using a motor in a drive system where the
motor nominal voltage differs from the AC power source voltage.
5. Ensure that the motor insulation system withstands the maximum peak voltage in
the motor terminals. See the Requirements table below for the required motor
insulation system and drive filtering.
Example 1: When the supply voltage is 440 V and the drive has a diode supply
and operates in motor mode only, the maximum peak voltage at the motor
terminals can be approximated as follows: 440 V × 1.35 × 2 = 1190 V. Check that
the motor insulation system withstands this voltage.
Example 2: When the supply voltage is 440 V and the drive is equipped with an
IGBT supply, the maximum peak voltage in the motor terminals can be
approximated as follows: 440 V × 1.41 × 2 = 1241 V. Check that the motor
insulation system withstands this voltage.
Protecting the motor insulation and bearings
The output of the drive comprises – regardless of output frequency – pulses of
approximately 1.35 times the equivalent mains network voltage with a very short rise
time. This is the case with all drives employing modern IGBT inverter technology.
The voltage of the pulses can be almost double at the motor terminals, depending on
the attenuation and reflection properties of the motor cable and the terminals. This in
turn can cause additional stress on the motor and motor cable insulation.
Modern variable speed drives with their fast rising voltage pulses and high switching
frequencies can cause current pulses that flow through the motor bearings, which
can gradually erode the bearing races and rolling elements.
If the drive is equipped with … … and … … then the motor voltage
rating should be …
diode supply
(ACS800-01, ACS800-U1,
ACS800-02, ACS800-U2,
ACS800-04, ACS800-04M,
ACS800-U4, ACS800-07,
ACS800-U7)
no resistor braking is used U
N
frequent or long-term brake cycles
are used
U
ACeq1
IGBT supply
(ACS800-11, ACS800-U11,
ACS800-17, ACS800-37)
DC link voltage is not increased from
nominal (through parameter settings)
U
N
DC link voltage is increased from
nominal (through parameter settings)
U
ACeq2
U
N
= Rated input voltage of drive
U
ACeq1
= U
DC
/ 1.35
U
ACeq2
= U
DC
/ 1.41
U
ACeq
= Equivalent AC power source voltage of drive in V AC
U
DC
= Maximum DC link voltage of drive in V DC. For resistor braking, U
DC
= 1.21 × nominal DC link
voltage. For units with IGBT supply: see the parameter value. Note: Nominal DC link voltage is U
N
× 1.35 or
U
N
× 1.41 in V DC.