Understanding Motor Performance Terms: A Quick Guide

2025-07-09 07:01

This guide explains common terms used in motor performance.
To choose the best motor for your product, it’s essential to understand these basic terms.
Let's review each term with an actual performance chart.

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1.Basic Terms for Motor Performance

1.1.Torque ( N ) [ Nm ]
1.2.Rotational Speed ( N ) [ r/min, rpm ]
1.3.Output ( P ) [ W ]

2.Explanation with Performance Specifications
3.FAQs

3.1.Is it safe to continue operating the motor beyond the rated voltage as long as it's within the operating voltage range?
3.2.When should instant maximum output and instant maximum torque be considered?

4.Conclusion

Basic Terms for Motor Performance

First, we'll look at three fundamental terms: torque, rotational speed, and output.
These terms are frequently used, so understanding them is key.

Torque ( N ) [ Nm ]

Torque, also known as twisting force, is the rotational power of the motor.
It’s represented by the symbol T and measured in Newton meters (Nm).

Torque roughly increases proportionally to the square of the voltage.
Therefore, increasing the voltage also increases the motor’s torque.

Rotational Speed ( N ) [ r/min, rpm ]

Rotational speed refers to how many times the motor's shaft rotates per minute.
It is represented by the symbol N and measured in revolutions per minute (r/min or rpm).
*Some motors may use revolutions per second (r/sec or rps).

Rotational speed is directly proportional to voltage.
Therefore, if voltage increases, the motor’s rotational speed also increases.

Output ( P ) [ W ]

Output, also called mechanical power, refers to the amount of work done per second.
It’s represented by the symbol P and measured in watts (W).

The output is proportional to the product of torque and rotational speed and can be calculated with the following formula:

Output P [W] = 2π × Torque T [Nm] × Rotational Speed N [r/min] ÷ 60
≈ Torque T [Nm] × Rotational Speed N [r/min] ÷ 9.55

Efficiency (η) is the percentage of input electrical energy converted to output mechanical energy:

Efficiency η [%] = Output P [W] ÷ Input P [W] × 100

A flowchart illustrating motor efficiency, with electrical input (voltage x current) converting to mechanical output (torque x speed).

Explanation with Performance Specifications

Now, let's take a look at the performance chart of our brushless motor, the MS-94BZA, and go over each performance term.

Performance Spec		Terminology Guide
Instant Maximum Output	342 W (10 sec max)	The maximum output that can be delivered momentarily.
Instant Maximum Torque	17.2 Nm (10 sec max)	The maximum torque that can be generated momentarily.
Rated Voltage	24 V	The recommended voltage for continuous and safe operation.
Rated Power	202 W	Mechanical output that can be delivered continuously and safely.
Rated Torque	8.6 Nm	Torque that can be generated continuously and safely.
Rated Speed	225 r/min	The speed at which the motor operates continuously and stably under the conditions of rated voltage and rated torque (load).
Operating Voltage	15-55V	The voltage applied to the motor during operation. The allowable voltage range is designed and predefined, and exceeding this range is not permitted.
Size	85.0 mm × 85.0 mm × Length : 84.5 mm	Motor Dimension
Weight	2.2 kg	Motor Weight
Reduction Ratio	10.33 : 1	The gear (reducer) reduces the motor's output by decreasing rotational speed and increasing torque. This ratio is typically calculated as "input speed ÷ output speed" and is is generally greater than 1.
Allowable Radial Load Bearing	700 N	The maximum load that can be applied perpendicular (radial direction) to the motor shaft.
Allowable Load Inertia	0.6 kg / m2 max (Applicable Acceleration Rate : 200 r/min/s)	The maximum load inertia that can be connected to the motor shaft while ensuring safe, stable operation, stopping, and control of the motor.
Withstand Voltage	500 V AC 1 minute (Between Terminal and Case)	An indicator of the maximum voltage that the motor's components and materials can withstand.
Insulation Resistance	10 MΩ (min.) (500 V DC)	An indicator that represents the insulation performance of motor components and materials.
Degree of Protection	IPx4 (Must use dedicated waterproof mating connector)	The IP (Ingress Protection) rating indicates a motor's ability to resist water intrusion. An "IPX4" rating means the motor can withstand water splashes from any direction without compromising its normal operation.

FAQs

In this section, we address common questions about motor performance terms.
Misunderstanding or misinterpreting these terms can lead to product failures or issues, so it’s important to be cautious.

Is it safe to continue operating the motor beyond the rated voltage as long as it's within the operating voltage range?

The motor can be used within the operating voltage range, but it is designed to operate at its rated voltage. For continuous and safe operation, we recommend using the motor at its rated voltage.

When should instant maximum output and instant maximum torque be considered?

These are important when lifting heavy loads, accelerating quickly, or when high torque is needed during startup. Insufficient torque at startup can cause delays in equipment activation, so be sure to check the instant maximum torque.

Conclusion

In this article, we provided a basic explanation of motor performance terms and further clarified each term by referring to the performance chart. Understanding these terms correctly is the first step in selecting the right motor for your application.

Mabuchi Motor offers a wide range of brushless motors to meet various needs. Please review the performance charts for each product and choose the motor that best suits your manufacturing requirements.

Explore our product lineup here.