Why Intelligent Motor Control
Motors play a very important role in running of processes. A starter provides a means of safely starting and stopping of the motors and protection from short circuit and overload. In conventional starters this protection is provided by means of a fuse and an overload relay respectively. Being mechanical devices, they have known limitations compared to the accuracy and reliability provided by electronic relays. Protection is provided to a motor primarily to prevent the loss of production, higher maintenance costs and unsafe conditions in a process, rather than saving the motor itself, which is inexpensive.
About 50% of motor trippings can be prevented by monitoring power and loading. Other failures can be prevented by having an effective asset management system. It is, therefore, necessary to have an “intelligent” protection system which can monitor the power supply and loading, identify the potential risks and send warnings and alarms to the maintenance staff. The system should also be able to monitor and record motor parameters and operating parameters such as the running hours and the number of starts/ stops that can help in carrying out timely preventive maintenance. The system should also have capability to transmit the real time parameter data and receive control orders through network protocols widely used in industrial automation.
Types of IMCC Components:
It has been found that over 90% of the motors in a typical process plant are upto 15 KW rating. Schneider offers complete intelligent motor starter unit ” Tesys U” for motors upto 15 KW rating. For motors beyond 15 KW rating Schneider offers intelligent motor relay “Tesys T” which is used along with a conventional motor starter. Upto 75KW motors, Tesys T has integral CTs. Beyond 75 KW external CTs are required for measurement. Where variable speed, softstarting and stopping is required, Schneider offers Altivar range of VFDs and Altistart range of soft-starters with advanced features and communication options. For power control, Schneider offers “NSX” range of intelligent MCCBs from 100A to 1200A, having integral measurement and communication. “Masterpact” ACBs with intelligent Micrologic E relay are available from 800A to 3200A.
The configuration and setting of all the above intelligent devices can be done with a PC or a laptop using “SoMove” software package, which is freely downloadable.
Tesys U Intelligent Motor Starter.
Tesys U consists of three components : Power Base, Control Unit and Communication Module as shown in the following diagram:
The power base is available in two models – up to 12A (5.5.KW) and up to 32A (15KW). Control Unit is available in three versions – Standard, Advanced and Multifunction. Communication module is available with widely used industrial protocols such as Asi, Modbus, Canopen, Profibus, Devicenet etc.
- Tesys U controller is extremely compact and has overall dimensions of 45x154x135 mm (WxHxD), and can be mounted side by side on DIN rail or fixed with screws.
- It is convenient to install Tesys U controllers in groups of 4 using a prefabricated 63A bus as shown in the following photograph:
- In the above configuration Tesys U controllers can be used over a wide operating temperature range of 0 to 70 Deg. C.
- Tesys U starters have a rated breaking capacity of 50 kA, which can be increased up to 130 kA by using external current limiting block.
- A variety of add on blocks are available for auxiliary contacts which can be used for hardwired indications, interlocks etc.
- Accessories such as phase barrier, door mounted handle are available
- Standard control units satisfy the basic requirements of protection – short circuit and overload. Advanced control unit allows additional advanced functions such as alarm, fault differentiation. Multifunction control unit is suitable for the most sophisticated control and protection requirements.
- Tesys U provides warnings for – Ground current fault, jamfault, current phase imbalance fault, under/ over current fault, under/ over voltage fault, under/ over power factor fault, communication loss fault
- Tesys U provides fault alarms for motor overload fault, motor over current fault, motor short circuit (to earth and phase to phase) fault, line supply under/ over voltage fault, line supply phase loss fault, motor phase loss fault, drive overheating fault, communication fault
- Tesys U provides measurements of line currents, average motor current, thermal capacity
- Communication modules are available with Asi bus, Modbus, Canopen bus, Profibus, Device Net protocols.
- Faults can be programmed to have manual, auto or remote reset.
- Motor can be operated in local or remote mode