Bypass Soft Starter Cabinet

The Bypass Soft Starter Cabinet is one of the main products manufactured by Yibaling Factory. It features excellent quality that exceeds national standards, and customers consistently place repeat orders. We look forward to becoming your long-term partner.

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Product Description

The bypass soft-start cabinet is an integrated and intelligent motor starting and control device. It ingeniously combines the thyristor soft-start unit with the bypass contactor system within a standard cabinet.
The core working mode is divided into two stages: When the motor starts, the voltage and current applied to the motor are precisely controlled by the soft starter inside the cabinet, achieving a smooth and impact-free soft start, effectively solving the problems of grid shock and mechanical stress caused by direct starting.

Online Soft-starting Cabinets VS. Bypass Soft-starting Cabinets

Name	Online Soft Starter Cabinet	Bypass Soft Starter Cabinet
Structural Composition	Mainly uses a soft starter as the control element, equipped with switches, cabinets, etc.	Based on the online type, an additional bypass contactor is added.
Working Principle	Thyristors continue to operate after the motor starts, providing smooth startup and normal operation.	After the startup is completed, the bypass contactor replaces the thyristors and provides the rated voltage to the motor.
Cost and Heat Generation	The cost of online soft starter cabinet is higher. During operation, the thyristors have on-state voltage drop, which will generate some heat.	The cost is low, it does not generate heat during operation, and the efficiency is close to 100%.
Applicable Scene	Online soft starter cabinets are required for full control and protection, dealing with applications featuring variable loads or fragile power sources, which are of critical and complex nature.	The bypass soft starter cabinet is only designed to handle the routine and stable load applications involving start-up and stoppage impacts.

Core Material

The core components of the bypass soft-start cabinet can be regarded as a system that is accomplished through the collaboration of several key parts:
The functional core lies in the thyristors (silicon-based semiconductors) of the soft-start unit and the large-capacity contactors (with silver alloy contacts) of the bypass unit.
The former achieves smooth voltage control during the startup stage, while the latter carries the full current during steady-state operation. The control core of the bypass soft-start cabinet is the built-in microprocessor chip, which is responsible for the logic and calculation of the entire system.
The electrical current path of the entire system is connected by high-purity copper busbars.
All components are installed on an anti-corrosion aluminum-zinc plated frame structure, and electrical safety is ensured by engineering plastic insulating parts.
For high-power models, aluminum alloy radiators and cooling fans are also equipped to handle heat, and a safety defense line is formed by protection components such as fuses and thermal relays.
The synergy of these materials ultimately achieves the design goals of smooth startup, efficient operation, and safety and reliability for the equipment.
The core materials used in our bypass soft-start cabinets have all been carefully selected by our Ibaling engineers and are of high quality. The bypass soft-start cabinets manufactured with these core materials have a quality far exceeding the standard and are highly stable in performance.

Testing Process

The factory test of the bypass soft starter cabinet is a rigorous, systematic verification process designed to simulate real operating conditions and ensure that the functions, safety, and reliability meet the standards. The entire process follows the principle of static first, then dynamic; separate components first, then the entire machine.
The first step is the separate and static test of the bypass soft starter cabinet. Without connecting to the main power supply, all core components inside the bypass soft start cabinet are individually tested, such as testing the mechanical characteristics and contact resistance of the bypass contactor, verifying the transformation ratio and polarity of the current/voltage transformers, and conducting 100% wiring correctness checks and insulation resistance (≥10MΩ) and power frequency withstand voltage (e.g. 2kV/1min) tests on all secondary control circuits to ensure basic safety and accuracy.
At the same time, according to customer requirements, preset the startup parameters and complete all functions tests of the human-machine interface.
Then, enter the core dynamic and functional testing stage. After connecting to the debugging power supply, first verify the phase sequence and voltage display of the main circuit. The most critical part is the bypass switching logic test, which requires using an oscilloscope to capture and verify that the thyristor output and the bypass contactor can achieve a smooth, arc-free, and impact-free switching at the zero-crossing point of the voltage. This is the core value of the bypass soft start cabinet's bypass design.
After that, connect the motor simulation load box or a small power motor to conduct a complete soft start and soft stop process test, and simulate various faults such as overcurrent, phase loss, and locked rotor to verify that all protection functions can act accurately and quickly according to the set values. Finally, perform a continuous load operation for several hours (aging test) during which an infrared thermal imager is used to monitor the temperature rise of key parts such as the thyristor heat sink and busbar connection points, ensuring that it remains within the safe limit (e.g. temperature rise ≤ 70K), to expose any potential process or design flaws.
After all tests are passed, conduct a final cleaning check, re-tighten the fasteners, and attach the complete "Factory Test Report for the Bypass Soft Start Cabinet" (including all measured data), drawings, certificates of conformity, etc., before packaging for shipment.