The SINAMICS S120 drive system

High degree of flexibility for successful
machine concepts
As a member of the new SINAMICS drive
family, the SINAMICS S120® drive is part
of the modular drive system for high-performance applications in machinery and
plant construction. SINAMICS S120 offers
high-performance single- and multi-axis
drives for an extremely wide range of industrial applications.
Through its scalability and flexibility,
SINAMICS S120 perfectly fulfills the
growing requirements relating to the
number of axes and performance.
SINAMICS S120 allows flexible machine
concepts to be created, which can be
used to quickly implement specific
customer requirements.
The response to increasing demands
Today, machines must be able to be
manufactured more cost-effectively and
at the same time they should offer operating companies increasingly higher levels
of productivity. The SINAMICS S120 drive
concept fulfills both of these tasks! Engineering times are shortened due to the
fact that it can be engineered in a userfriendly fashion. Its high dynamic performance and accuracy permits higher cyclic
machine rates for a maximum
degree of productivity. Not only this, its
simple handling and maintenance increases the degree of availability and reduces the life cycle costs. When considering
everything: SINAMICS S120 increases the
competitiveness of both machine manufacturers and operating companies.
Modularity for machine construction
SINAMICS S120 allows power and control
performance to be freely combined.
Multi-axis drive solutions with higherlevel motion control can be implemented
using the modular SINAMICS S120 drive
system just the same as solutions involving single-motor drives. This means that
the machines can be designed to be
fully modular therefore addressing the
growing number of different versions.
Where modules or individual components
are to be combined or innovated,
SINAMICS S120 guarantees the perfect
compatibility between all of the system
components without requiring any major
engineering costs.
Applications in machine and plant
construction
SINAMICS S120 means increased
machine performance in many sectors –
whether continuous material webs or
cyclic and high-dynamic processes, for
instance in:
• Packaging machines
• Plastics machines
• Textile machines
• Printing machines
• Paper machines
• Handling and assembly systems
• Machine tools
• Rolling mills
• Test stands

Digital microprocessor-controlled power converter technology

Digital microprocessor-controlled power converter technology, both for DC and AC drives, has
now reached a level of technical sophistication
which (in purely technological terms) enables
almost any drive job to be handled both with DC
and AC drives. Nevertheless, the conventional
DC drive (in both its 1-quadrant and 4-quadrant
variants) will continue to play an important role,
for technical and physical reasons alike, when
dynamic drives with a constant load torque and
stringent requirements for overload withstand
capability throughout a large speed setting range
are involved.

Efficiency and operating point of DC and AC standard motors

The motor constant makes it possible to design the nominal point of DC motors corresponding to the process requirements.
However the efficiency of AC motors is better (> 55 kW: approx. 1 ... 4 % depending on cooling method).
DC motors are often utilized according to insulation class H. Standard AC motors are used to be utilized according to insulation
class B. This results in a possible higher efficency with AC motors.

Degree of protection for motors, Ac Dc Motor

The historical development of the DC motor as an electric variable-speed drive since the beginning of the twenties has meant
that DC motors are customarily used with internal/forced ventilation (approx. 85 % of VSDs ≤ 250 kW).
For variable-speed AC drives, asynchronous standard motors have predominantly been utilized since the 70s/80s, which mostly
feature surface ventilation (approx. 90 % of VSDs ≤ 250 kW). Thus the process of matching the three-phase standard motors
to the requirements applying for variable-speed drives with AC converters has not yet been concluded.
The fact that AC motors with ratings of up to approx. 1400 kW are supplied in degree of protection IP 54 as standard is a tribute
to their simple and sturdy construction. For drive jobs in hazardous areas, explosion-protected AC motors are used almost
exclusively. This means that the AC motor has won itself a firm position and proved its practical utility most especially in those
sectors of industry characterized by aggressive ambient conditions and a high degree of dirt and dust in the cooling air.

High speed setting range at constant power (field weakening operation or field control range)

For specialized drive jobs, like coiler drives, test rigs, winders and unwinders, etc., very large setting ranges at constant power
are stipulated. In these cases, conventional field weakening operation with an externally excited DC machine makes
implementation particularly cost-efficient. This means: the larger the speed range in which a motor can output its maximum
power (length of the horizontal section of the characteristic in Fig. 5, from nG
 to n
1
), the smaller the overdimensioning factor
can be kept Pmax(motor)
/ Pmax(load)
.
Values obtained from empirical feedback:
A typical value for the field weakening range of DC Motors
with a shaft height of 112 ... 225 mm in the rating category of
5 ... 360 kW (M ≤ 2900 Nm) is 1 : 3.
The maximum value for the field weakening range at compensated DC motors with a shaft height of ≥ 250 mm in the
rating category of 125 ... 1400 kW (M = 2400 ... 24500 Nm)
is 1 : 5.
Example: compensated DC Motor DMA + 280 K (see Fig. 5)
nG
n
1
nmax
Speed n (rpm) 0 500 1500 2500
Power P (kW) 0 130 130 80
Torque (Nm) 2483 2483 827 305
Values obtained from empirical feedback:
Due to the pull-out torque  Mk
 ≈  MN
  x  2,5, the  typical value
for the field weakening range is only 1 : 1.5 up to a maximum
of 1 : 2.5 for all standard AC Motors.
Example: AC Standard Motor ...450LL12 (see Fig. 5)
nG
nmax
Speed n (rpm) 0 500 1250
Power P (kW) 0 130 130
Torque (Nm) 2483 2483 933