High motor starting current is a common problem in industrial plants. When a large motor starts directly, it may cause voltage drops, circuit breaker trips, transformer stress, mechanical shock, and unexpected downtime. For pumps, fans, compressors, conveyors, crushers, and mills, poor starting performance can directly affect production stability and maintenance cost.
Why Is High Starting Current a Problem?
Large motors usually draw much more current when they start up than during normal operation. This sudden current impact can create voltage dips, overheating, contactor wear, motor insulation stress and mechanical shock. In some plants, frequent motor starting increases the risk of equipment failure and production interruption.
For industrial users the real problem is not only the starting current. The larger problem is the cost of unstable operation, emergency maintenance and downtime.
Soft Starter or VFD: Which One Should You Choose?
Soft starters are primarily used to limit the starting current and to provide a smooth acceleration of the motor. It is suitable for applications in which the motor normally runs at constant speed after the start. If you are concerned about high inrush current, voltage dips or mechanical impact, a soft starter can be a viable and cost-effective solution.
A VFD can control motor start and running speed. It is more suitable for applications requiring speed regulation, energy saving, pressure control, flow control or process optimization. VFD control is often beneficial for pumps, fans, compressors, HVAC systems and cooling systems, because the motor doesn't always need to run at full speed.
Key Factors Before Selecting a Solution
Users should consider motor power, voltage, rated current, load type, starting frequency, starting torque, grid capacity, site environment and control requirements when choosing soft starter or VFD. For heavy-duty loads or medium voltage motors, selection must be more careful to avoid overheating, trips or unstable operation.
The selection of the solution should be based on real operating conditions, not only on motor kW.
Reliability Is More Important Than the Lowest Price
Industrial buyers should not always go for the lowest first price. The cost of an unplanned shutdown may be higher than the difference between two motor control solutions. A good solution should reduce the impact on start up, protect equipment, improve system stability and support for long term operation.
RENLE Motor Control Solutions for Industrial Applications
RENLE offers soft starters, low-voltage VFDs, medium-voltage soft starters and medium-voltage VFD solutions for industrial motor control applications. These solutions are used in pumps, fans, compressors, conveyors, water treatment, mining, cement, petrochemical, metallurgy, power generation and other industrial sites.
If your plant is suffering from high starting current, voltage dips, frequent tripping or mechanical shock when the motor starts, please contact RENLE with your motor data and site conditions. Our team can help recommend the right motor control solution for your project.
