ZF-R Series Current-Controlled Motor Soft Starter

Current-Controlled Soft Start is a technology that achieves smooth motor starting by limiting the starting current. Its core principle involves regulating the input current of the motor through power electronic devices (such as thyristors) to gradually increase it during the starting process until it reaches the rated value. During startup, the current is restricted within a preset limit to prevent excessive current surges that could damage the power grid and equipment. Once the motor reaches its rated speed, the soft starter automatically replaces the thyristors (which have completed their task) with a bypass contactor, providing the motor with the rated voltage for normal operation.

Features and Advantages

1. Low Inrush Current: By limiting the starting current, it effectively reduces the current surge during startup, protecting the power grid and equipment.
2. Smooth Torque Rise: During the starting process, the torque increases smoothly, protecting the transmission machinery, equipment, and personnel.
3. Stepless Regulation: Current-controlled soft starters employ power semiconductor switches to achieve stepless regulation, enabling continuous and stable motor starting.
4. Protection Functions: Equipped with multiple protection features such as overcurrent protection, overload protection, and phase loss protection, it enhances system reliability and safety.

Application Scenarios

Current-controlled soft starters are widely used in applications where starting current needs to be limited, such as:

• Industrial Production: Used in automated production lines, large fans, pumps, and other equipment to reduce mechanical and electrical shock during startup.
• Building Equipment: Such as elevators and air conditioning systems, to reduce startup noise and extend equipment lifespan.
• Power Systems: Applied in substations and distribution lines to enhance power system stability.
• Transportation Facilities: In motor startups for subways, light rail, and other transportation facilities to reduce grid impact.

Technical Implementation

1. Thyristor Control: Utilizes thyristor phase control technology to regulate the motor's input voltage, achieving precise current control by adjusting the thyristor's conduction angle.
2. Intelligent Control Algorithms: Employs advanced control algorithms to freely and steplessly adjust to the optimal starting current based on load conditions and grid relay protection characteristics.
3. Microcomputer Control and Fault Diagnosis: Conducts pre-startup fault diagnosis on the main circuit to improve system reliability.

Advantages

• • Reduces current surge during startup, protecting circuit components.
  • Lowers starting current to prevent startup overcurrent tripping.
  • Can incorporate current closed-loop control to ensure smooth motor startup.