Large electric motors can draw significantly more current when starting. This can cause voltage dips, tripping of breakers, and mechanical stress on belts, couplings, pumps, and gearboxes. A bypass intelligent motor soft starter offers a better and simpler solution for the start and stop of fixed-speed motors.
What Is a Bypass Intelligent Soft Starter?
A bypass intelligent soft starter utilizes SCRs or thyristors to govern motor acceleration. Additionally, it is capable of providing adjustable ramp-up and ramp-down times, as well as current limiting, overload protection, phase loss detection, fault logging, and connection with PLC and SCADA systems.
The contactor in bypass mode can either be incorporated into the system or put in a different location. The Bypass Soft Starter which has an inbuilt contactor is easy to manage and deploy. The external bypass soft starter gives more opportunities for unique control cabinets.
How the Bypass Function Works
- The starter receives a start command and checks the motor conditions.
- It gradually increases voltage to control motor acceleration.
- When the motor reaches the required speed, the bypass contactor closes.
- The contactor carries the running current while the SCRs stop conducting.
In a soft stop, the contactor opens ahead of any electronic actions or processes, which allows the speed of the motor to be decreased gradually. This can prevent water hammer in pumps and abrupt strain on conveyors and other devices.
Key Benefits
A bypass intelligent soft starter can:
- Reduce starting current and voltage drops
- Limit mechanical shock during acceleration
- Reduce heat during normal motor operation
- Provide controlled stopping
- Display operating data and fault information
- Support remote monitoring and industrial communication
Best Applications
| Application | Main Benefit |
|---|---|
| Water and wastewater pumps | Reduces pressure surges and starting current |
| Fans and HVAC systems | Protects belts, bearings, and electrical equipment |
| Conveyors | Reduces belt shock and product movement |
| Compressors and mixers | Provides smoother acceleration |
Soft starters are a good solution when a motor runs at only one speed. However, in situations where a variable speed or energy efficiency through speed variations is desirable, a variable speed drive may offer a better solution.
How to Choose the Right Model
You need to verify the motor’s voltage, frequency, phase, nameplate current, starting torque, time taken for acceleration, the number of starts allowed in an hour. You should review the environmental temperature, type of ventilation, effect of safety regulations, protocols for communication and local electricity regulations.
Choosing a starter is based on the prevailing current and load conditions rather than only on horsepower. A qualified electrician must oversee the installation process, including all the wiring, grounding, protection, and commissioning.
Frequently Asked Questions
What is a bypass intelligent soft starter?
The term ‘motor controller’ describes a device that allows for regulated start-up and stop of the motor after which it allows the running current to flow through a bypass contactor.
Does it save energy?
The primary purpose of this device is to provide smooth motor start. Although the bypass contactor is useful for reduced heating and energy losses, variable frequency drives generally achieve a more efficient energy-saving capability depending on speed needs.
What is the difference between built-in and external bypass?
A bypass soft starter that is built-in has an integrated contactor in the package. On the contrary, an external bypass soft starter consists of a separate contactor and therefore offers more flexibility in designing custom panels.
When properly chosen, a Bypass Soft Starter can decrease electrical information, mechanical load, and temperature in operation while ensuring dependable fixed-speed control of engines. With suitable design and installation, this is a feasible choice for pumps, fans, conveyors, compressors, and countless other industrial devices.
Post time: Sep-08-2026