Clever Motor Starting with SIRIUS and SINAMICS

Starting motors. This sounds much easier than it is. Fact is that
three-phase asynchronous motors are the most widely used electric
motors in industry. To start and control them, there are a number of
products to choose from, ranging from simple contactor-motor starter
protector combinations to soft starters and frequency converters.

But what is the right solution?

Siemens offers a wide range of motor starting solution fitting perfectly
for many applications with different technical requirements. 

• SIRIUS motor starter protector (circuit-breakers) in
combination with a
o SIRIUS contactor
o SIRIUS reversing contactor
o SIRIUS solid-state contactor
o SIRIUS motor starter
o SIMATIC ET 200SP motor starter
• SIRIUS star-delta combination
• SIRIUS soft starter
• SINAMICS frequency converters

Check which applicatons suits you best in the infograph. 

AThe direct-on-line start and reversing start are conventionally implemented
electromechanically using a combination of circuit breaker and contactor or
contactor and overload relay. With so-called motor starters, however, compact devices are also available that combine both fu nctions in one device. 

Benefits:
- Low-cost acquisition
- Suitable for Safe Torque Off (STO) due to electrical isolation
- Fast ramp-up based on maximum torque
­- Easy configuration
- Easy maintenance
- Proven and available worldwide
- Low power cost

Application area:
- Universal use
- Motors up to 250 kW that can be operated at fixed speed and directly  started

The starting of a motor with a contactor assembly for star delta start requires
three contactors: star contactor, delta contactor and line contactor. With the
star-delta start, the starting current is reduced to approximately 1/3 due to the
star connection. Once the motor has reached its rated torque, the star
connection changes over to delta connection with the help of a special timing
relay. This produces a further smaller current spike, which, however, is
significantly lower overall than that of the direct-on-line start.

Benefits
- Reduced starting current
- Medium to high power range (>7.5kW)
- Low power loss
- Suitable for safety applications / electrical isolation
- Preassemled star-delta startner available
- Simple technology for global use

Application areas
- Universal use
- Applications in which starting current spikes must be avoided
- Applications in which torque spikes must be prevented
- Larger motors up to approx. 500 kW

Soft starters limit the inrush current and thus also the starting torque. The stress on the mechanical components of the drive train is reduced in comparison with direct start and uncontrolled ramp-up of the motor. Typical areas of use for a soft starter are, for example, pumps, fans, compressors, conveyor belts, belt drives or escalators. These applications require continuous stepless speed adjustment up to rated speed as well as torque limitation during starting and stopping. Soft starters are significantly more compact and cheaper to purchase than frequency converters, and their maintenance requirement is low. What is more, the integrated bypass function reduces the loss of energy during operation. When they are used in control cabinets, one positive aspect is that there is no additional heat generation, which means that there is frequently no need for additional air-conditioning equipment.

Benefits
- Modern hybrid switching technology for an energy-saving and long service life
- Protection of your network, motor and load against overload
- Perfect drive solution for applications with fixed speed
- No additional heat production because of integrated bypass contacts

In the case of variable process parameters, such as where there is a process-dependent compressed air demand, the energy consumption of the system can be optimally adjusted to the actual demand. Typical applications would include the operation of fans, pumps or compressors. Another advantage of frequency converter is that they enable an ideal adaptation to the application thanks to several product-integrated functions and options. Thus, the frequency converter is also user-friendly and flexible, for example in cases in which a speed adjustment may be necessary to change goods being produced.

Benefits:
- Perfect for applications with variable speed; adjustable to variable process
parameter
- Simple installation, service and maintenance
- Robust and compact system for tough application environments
- Cost reductions due to savings in energy and electrical operating costs
Picture

Application Areas:
- Multi-purpose applications (variable speed)
- Applications having power requirements that cannot be
precisely planned (variable adjustment of the motor
power to the actual requirement to increase energy efficiency