Siemens Agriculture Starter complying to latest standards User Manual
Agriculture Starter complying
to latest standards
Automatic Star Delta Starters IEC 60947-4-1:
2012 Compliant
Direct-on-Line Starters ISI Marked-BIS Approved
www.siemens.co.in
Tried, Tested and Trusted Start with Siemens Agriculture
Starters
For more than 125 years, Siemens has been developing and manufacturing world-class, control
products. Siemens offers a wide range of starters to cater to diversied demands from Agriculture
Sector .These products are specially designed to provide smart, easy and reliable motor starting
solution.
They employ tried and tested Siemens contactors and relay and this ensures the right start for motors
requiring direct online starting or star delta starting.
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Direct on Line Starter (DOL) RAJA
3TW7291-1A...
Range: 0.25kW to 7.5kW
0.33HP to 10HP
Method of starting
A. DOL starting method:
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The most economical and popular method of starting squirrel cage induction motors, is direct-online, where the starter is connected directly across the supply. However, the starting current at the
moment of switching Direct-on-line can be as high as 6-8 times the rated current.
Advantages:
High starting torque, shorter starting time, simple construction and wiring, space saving etc.
Disadvantages:
High starting current
Applications:
DOL: As we know, A direct on line starter can be used if the high inrush current of the motor does
not cause excessive voltage drop in the supply circuit. It can be used to start small agriculture water
pumps, compressors, fans and conveyor belts etc.
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Construction
Availability of Agriculture starters in new design: DOL - 15th Dec. 2020 | ASD - 15th Feb. 2021
Contactor:
The DOL starter up to 10 HP is tted with 3TS3 Contactor. This contactor is specially designed by
Siemens considering the requirements of industry as well as agriculture. Considering the specic
need of the agricultural pump set applications, Siemens has designed a special wide band coil
(200- 400V). This coil operates reliably even when there is wide voltage uctuation.
The Starters will now come with 3TS Contactors which will in turn make the starter more reliable
with enhanced electrical and mechanical life.
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Bimetal Overload Relay:
The RAJA direct-on-line starter is tted with 3UW5 relay. These relays are computer calibrated and
therefore, offer accurate protection. The main benet of this bimetal relay is the built-in single
phasing protection in addition to the overload protection. Relay has Automatic reset function after
cooling time of 4 sec approx, completely reduce Manual dependency.
Push buttons
Push buttons are used for switching ‘ON’ and ‘OFF’ the starter. Twin push button comes with ‘Locked
Off’ feature which helps in avoiding nuisance switching ON of pump.
Operation:
In DOL starting, the ‘ON’ push button is pressed, which energizes the contactor coil, thus switching
on the circuit. When the OFF’ push button is pressed, the contactor is de-energized, switching off
the circuit. The bimetal relay under normal functioning of motor plays no active part in the starter.
But under overload, single phasing or locked rotor conditions of Motor, the bimetal relay cuts-off
the supply to the contactor coil, tripping the circuit. The contactor itself provides the necessary ‘novoltage’ protection in so far as it will drop out in the case of a supply failure, and for restarting on
resumption of supply, the ‘ON’ push button will have to be pressed again.
Reliability:
• 3TW72 range of DOL starters are having option of 200-400 V Coil voltage which takes care of wide
uctuations in supply.
• Accurate protection under single phasing & overload.
• With ISI marking, it ensures more safety for the end user.
• With 3TS contactors tted into it, ensures more electrical and mechanical life of the Starter.
• With Locked off feature, ensures that undesirable switching on of the Starter is prohibited.
• No Auto start only Auto reset of Bimetal relay and it needs Manual Acknowledgement to again
ON the Starter.
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