Low Voltage Motors In Variable Speed Operation; Introduction; Winding Insulation; Selection Of Winding Insulation For Abb Converters - ABB MT Série Manuel D'installation, D'exploitation Et De Maintenance

6. Low voltage motors in variable speed operation

6.1 Introduction

This part of the manual provides additional instructions for
motors used in frequency converter supplies. The motor
is intended to operate from a single frequency converter
supply and not motors running in parallel from one
frequency converter. Instructions given by the converter
manufacturer shall be followed.
Additional information may be required by ABB to decide
on the suitability for some motor types used in special
applications or with special design modifications.

6.2 Winding insulation

Variable speed drives create higher voltage stresses
than the sinusoidal supply on the winding of the motor.
Therefore, the winding insulation of the motor as well as
the filter at the converter output must be dimensioned
according following instructions.
6.2.1 Selection of winding insulation for
ABB converters
In the case of ABB e.g. AC_8_ _-series and AC_5_ _-series
single drives with a diode supply unit (uncontrolled DC
voltage), the selection of winding insulation and filters can
be made according to table 6.1.
U ≤ 500 V
N
500V >U ≤ 600V
N
500V >U ≤ 600V
N
(cable length > 150 m)
600V >U ≤ 690V
N
≤ 690V
600V >U
N
(cable length > 150 m)
Table 6.1 Selection of winding insulation for ABB converters
Please contact ABB for more information on resistor braking and converters with controlled supply units.
Standard_Manual_LV_Motors_ML_revF_Book.indb 11
P < 100 kW P ≥ 100 kW or
N N
IEC315 ≤ Frame size ≤ IEC355
Standard motor Standard motor
+ Insulated N-bearing
Standard motor Standard motor
+ dU/dt –filter (reactor) + dU/dt –filter (reactor)
OR + Insulated N-bearing
Reinforced insulation OR
Reinforced insulation
+ Insulated N-bearing
Standard motor Standard motor
+ Insulated N-bearing
Reinforced insulation Reinforced insulation
+ dU/dt –filter (reactor) + dU/dt –filter (reactor)
+ Insulated N-bearing
Reinforced insulation Reinforced insulation
+ Insulated N-bearing
Low voltage motors manual, 3GZF500730-85 Rev F 02-2015 | ABB Motors and Generators 11
6.2.2 Selection of winding insulation with
all other converters
The voltage stresses must be limited below accepted limits.
Please contact the system supplier to ensure the safety of
the application. The influence of possible filters must be
taken into account while dimensioning the motor.

6.3 Thermal protection

Most of the motors covered by this manual are equipped
with PTC thermistors or other type of RTD's in the stator
windings. It is recommended to connect those to the
frequency converter. Read more in chapter 4.9.2.

6.4 Bearing currents

Insulated bearings or bearing constructions, common
mode filters and suitable cabling and grounding methods
must be used according to the following instructions and
using table 6.1.
6.4.1 Elimination of bearing currents with
ABB converters
In case of ABB frequency converter e.g. AC_8_ _- and
AC_5_ _-series with a diode supply unit, the methods
according to table 6.1 must be used to avoid harmful
bearing currents in motors.
P ≥ 350 kW or
N
IEC400 ≤ Frame size ≤ IEC450
Standard motor
+ Insulated N-bearing
+ Common mode filter
Standard motor
+ Insulated N-bearing
+ dU/dt –filter (reactor)
+ Common mode filter
OR
Reinforced insulation
+ Insulated N-bearing
+ Common mode filter
Standard motor
+ Insulated N-bearing
+ Common mode filter
Reinforced insulation
+ Insulated N-bearing
+ dU/dt –filter (reactor)
+ Common mode filter
Reinforced insulation
+ Insulated N-bearing
+ Common mode filter
6/2/2015 6:44:25 PM