low-voltage

Squirrel-cage motors
Technical information
Converter-fed operation
In general, all motors are suitable
for converter-fed opera-
2
tion. Some motors require special
measures.
The planning notes for drives
with a constant or square-law
counter-torque are contained in
the following catalogues:
MICROMASTER:
Catalogue series DA 64 and
DA 51
SIMOVERT MASTERDRIVES:
Catalogue series DA 65
These catalogues also contain
tables showing which squirrelcage
motors should be assigned
to which SIMOVERT
converter, depending on the
load characteristic of the driven
machine.
■All data specified in Catalogue
M11 applies to 50 Hz supply
systems.
Attention should be paid to the
reduction factors for constanttorque
drives, pump drives and
compressor drives.
Motor temperature detection
KTY 84 temperature sensor:
Order Code:
A23 = 1 x KTY 84-130,
A25 = 2 x KTY 84-130
This sensor is a PTC thermistor.
Its resistance varies as a function
of the temperature in accordance
with a defined curve.
Some Siemens converters calculate
the motor temperature
according to the resistance of
the temperature sensor. They
can be set to a user-definable
temperature for alarms and
tripping.
The 1LA8 motors are supplied
without the standard PTC thermistor
if Order Code A23 is
specified.
The temperature sensor is embedded
in the motor winding
overhang in the same way as a
PTC thermistor. The evaluation
is effected by the converter, for
example.
The 3RS10 temperature monitoring
device belonging to the
protection device can be ordered
separately for mains-fed
operation. For further details
see Catalogue CA 01 Order No.
E86060-D4001-A110-C1-7600.
Motor protection
All standard 1LA and 1LG motors
for Zones 2, 21, and 22 for
converter-fed operation are already
fitted with a PTC thermistor
for tripping. It is also possible
to order a PTC thermistor
for alarm for converter-fed operation
(Order Code A10).
Insulation
The insulation of 1LA and 1LG
motors is such that they can operate
unrestrictedly in converter-fed
mode up to voltages of
ˆ 500 V. The same applies to
operation with pulse-controlled
AC converters with voltage front
times t s > 0.1 ms at the motor terminals.
Providing these conditions are
met, all motors with voltage
codes 1, 3, 5, and 6 can be operated
in converter-fed mode,
except for those with voltage
ratings of > 500 V to 690 V,
which are supplied with special
insulation for operation with a
pulse-controlled AC converter
(SIMOVERT MASTERDRIVES,
MM440 > 500 V – 600 V) but
without a converter circuit (du/dt
filter or sine filter) (10th position
of the Order No. = "M").
For operation with a converter at
the outputs specified in the catalogue,
the motors are utilized
according to temperature class
F. Order Codes C11, C12 and
C13 are not possible.
Connection of the motors
In addition to the restrictions applying
to mains-connected machines,
the maximum permissible
conductor cross-sections
for the converter must also be
kept in mind when the motors
are connected.
Ventilation/
noise
Increased fan noise may occur
in self-ventilated motors at
speeds higher than the rated
speed.
To increase motor utilization for
low speeds, it is advisable to
use separately ventilated motors
such as 1LA5, 1LA7, 1LG,
and 1LG6 with Order Code G17
or motor 1PQ8.
Mechanical stress, grease life
Due to the higher speeds beyond
the rated speed value and
the resulting increased vibration,
the mechanical balance
quality changes and the bearings
are under greater mechanical
stress. This reduces the
grease life and the bearing life.
(enquire if necessary).
Bearings
To avoid damage by bearing
currents, isolated bearings for
frame sizes 225 to 315 are available
and recommended for
frame size 280 (Order Code
L27) 1 ). These are standard in
1LA8 motors for converter-fed
operation on SIMOVERT
MASTERDRIVES (9 th position
of the Order No. = "P").
3
M1-5178
R
2
k
1
D = 2 mA
0
0
100
°C
200
T U
300
1) For 1MJ7 motors, Order Code
L27 can be used for frame sizes
250 to 315.
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Siemens M 11 · 2003/2004