What to Use on VFD – Inverter-Duty Motor or Standard Motor

If you’re into variable speed pumping, you might come across motors driven by variable frequency drives (VFDs) that have outpaced the entire industry. Keep in mind, the more demanding and complex the application is, the more specifications motor needs to accommodate for superior results. 

And that’s where the question arises, whether to use a standard or inverter-duty motor on VFD? Let us explain a bit. The term inverter-duty is referred to a motor whose speed is controlled and managed by an inverter or VFD. While both standard and the inverter-duty motor operate well under VFD, the significant difference lies within construction and capability.

What’s the Difference – Standard vs Inverter-Duty Motor

The standard motor is good for use with VFD but doesn’t have the speed adjustability that the inverter-duty motor offers. It creates a steady flow of power with a few voltage peaks and line noise, making it a good fit for basic applications. 

But the disadvantage is this motor works only at a single speed. So, if you need a motor that runs at variable speed, go for an inverter-duty motor. It primarily takes AC power and turns it into DC, where wavelength and frequency can be controlled. 

As it is important to comprehend systems’ demand and application requirements, look for genuine frequency inverter suppliers to get efficient solutions.

3 Applications to Determine Which Motor Would Work Best

1. Does application involve constant torque or variable torque?

The primary factor to decide when to use inverter-duty or standard motor is torque capability. Constant torque applications like general machines or conveyors may require the same level of torque throughout the speed range. As an inverter-duty motor can work at low speed and doesn’t overheat, it is capable of producing a broad torque speed range than a standard motor.

Variable torque applications, on the other hand, would need more torque as speed increases. Standard motors don’t overheat in case of reduced torque and low-speed requirements. Hence, variable torque is combined with standard torque for effective procedure.

2. What’s the minimum and maximum RPM speed the motor will be operating at?

Based on the size and type, a standard, enclosed fan-cooled motor is capable of 4:1 up to 10:1 consistent torque speed range. If an application needs a speed range beyond this, an inverter-duty motor must be considered as it can accommodate speeds ranging up to 1000:1 or above and provide full-rated torque at zero speed.

3. What’s the duty cycle and dynamic performance required?

Determine a motor’s duty cycle, how many times it starts and stops per hour, how often it is required to load up to speed, and dynamic performance to decide which kind of motor would work perfectly. 

In applications where speed synchronization is crucial for production quality, inverter-duty motors equipped with encoders are used to get rotor speed and position information. When required, the inverter-duty motor can provide broad speed ranges, encoder kits, and motor cooling designs for operating at slow speed.

Shenzhen Veikong Electric CO., Ltd. is a leading variable frequency drive manufacturer that works through vector control, SPWM, and torque control technology in VFD series inverter to reach the optimal level. With quality control and high industry standards, you will rest assured knowing you get valuable and best-performing solutions at all times.

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