A duty cycle or power cycle is the fraction of one period in which a signal or system is active. A period is the time it takes for a signal to complete an on-and-off cycle. Duty cycles can be used to describe the percent time of an active signal in an electrical device such as the power switch in a switching power supply or the firing of action potentials by a living system such as a neuron. In electronics, duty cycle is the percentage of the ratio of pulse duration, or pulse width PW to the total period T of the waveform.
It is generally used to represent time duration of a pulse when it is high 1. In digital electronics, signals are used in rectangular waveform which are represented by logic 1 and logic 0.
Logic 1 stands for presence of an electric pulse and 0 for absence of an electric pulse. Pulse-width modulation PWM is used in a variety of electronic situations, such as power delivery and voltage regulation. In electronic music, music synthesizers vary the duty cycle of their audio-frequency oscillators to obtain a subtle effect on the tone colors. This technique is known as pulse-width modulation.
In a welding power supplythe maximum duty cycle is defined as the percentage of time in a minute period that it can be operated continuously before overheating. The concept of duty cycles is also used to describe the activity of neurons and muscle fibers. In neural circuits for example, a duty cycle specifically refers to the proportion of a cycle period in which a neuron remains active. From Wikipedia, the free encyclopedia. Play media. Microcontrollers Fundamentals for Engineers and Scientists.
Morgan and Claypool Publishers. Fundamentals of Linear Electronics: Integrated and Discrete 2 ed. Cengage Learning. Boulder, Colorado: Institute for Telecommunication Sciences. Retrieved March 3, Dynamic biological networks: the stomatogastric nervous system. Massachusetts: MIT Press. Graf IEC the International Electrotechnical Commission uses eight duty cycle designations to describe electrical motors operating conditions:. Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro.
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Please read AddThis Privacy for more information. If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords. IEC the International Electrotechnical Commission uses eight duty cycle designations to describe electrical motors operating conditions: S1 Continuous duty The motor works at a constant load for enough time to reach temperature equilibrium. S2 Short-time duty The motor works at a constant load, but not long enough to reach temperature equilibrium.
The rest periods are long enough for the motor to reach ambient temperature. S3 Intermittent periodic duty Sequential, identical run and rest cycles with constant load.
Temperature equilibrium is never reached. Starting current has little effect on temperature rise. S4 Intermittent periodic duty with starting Sequential, identical start, run and rest cycles with constant load. Temperature equilibrium is not reached, but starting current affects temperature rise. S5 Intermittent periodic duty with electric braking Sequential, identical cycles of starting, running at constant load and running with no load.
No rest periods. S6 Continuous operation with intermittent load Sequential, identical cycles of running with constant load and running with no load. S7 Continuous operation with electric braking Sequential identical cycles of starting, running at constant load and electric braking.
S8 Continuous operation with periodic changes in load and speed Sequential, identical duty cycles run at constant load and given speed, then run at other constant loads and speeds. Privacy We don't collect information from our users.
Citation This page can be cited as Engineering ToolBox, IEC Duty Cycles. Modify access date. Scientific Online Calculator. Make Shortcut to Home Screen? The motor works at a constant load for enough time to reach temperature equilibrium.
The motor works at a constant load, but not long enough to reach temperature equilibrium.The table below lists the nine IEC duty cycles and their individual characteristics:. Labels: Electric Motors. Newer Post Older Post Home. You May Also Like:.
Operation at constant load of sufficient duration to reach the thermal equilibrium. Operation at constant load during a given time, less than required to reach the thermal equilibrium, followed by a rest enabling the machine to reach a temperature similar to that of the coolant 2 Kelvin tolerance. A sequence of identical duty cycles, each including a period of operation at constant load and a rest without connection to the mains.
For this type of duty, the starting current does not significantly affect the temperature rise. A sequence of identical duty cycles, each consisting of a significant period of starting, a period under constant load and a rest period. A sequence of identical cycles, each consisting of a period of starting, a period of operation at constant load, followed by rapid electric braking and a rest period.
A sequence of identical duty cycles, each consisting of a period of operation at constant load and a period of operation at no-load. There is no rest period. A sequence of identical duty cycles, each consisting of a period of starting, a period of operation at constant load, followed by an electric braking.
A sequence of identical duty cycles, each consisting of a period of operation at constant load corresponding to a predetermined speed of rotation, followed by one or more periods of operation at another constant load corresponding to the different speeds of rotation e. The period of duty is too short to reach the thermal equilibrium. Duty in which, generally, the load and the speed vary non-periodically within the permissible range.
This duty includes frequent overloads that may exceed the full loads.Motors convert electrical energy into mechanical energy. A stepper motor converts electrical pulses into specific rotational movements.
The movement created by each pulse is precise and repeatable, which is why stepper motors are so effective for positioning applications. Permanent Magnet stepper motors incorporate a permanent magnet rotor, coil windings and magnetically conductive stators. Energizing a coil winding creates an electromagnetic field with a north and south pole as shown in figure 1. The stator carries the magnetic field which causes the rotor to align itself with the magnetic field.
Figure 1: Magnetic field created by energizing a coil winding. Figure 2 illustrates a typical step sequence for a two phase motor. In Step 1 phase A of a two phase stator is energized. This magnetically locks the rotor in the position shown, since unlike poles attract.
In Step 3, phase B is turned off and phase A is turned on but with the polarity reversed from Step 1. In Step 4, phase A is turned off and phase B is turned on, with polarity reversed from Step 2. Figure 2: "One phase on" stepping sequence for two phase motor. However, only the polarity of one phase is switched at a time, as shown in figure 3. Since both phases are always on, this method gives Figure 3: "Two phase on" stepping sequence for two phase motor. Since one of the windings is not energized during each alternating half step there is less electromagnetic force exerted on the rotor resulting in a net loss of torque.
By reversing the current in the windings, electromagnetic polarity is reversed. The output stage of a typical two phase bipolar drive is further illustrated in the electrical schematic diagram and stepping sequence in figure 5. As illustrated, switching simply reverses the current flow through the winding thereby changing the polarity of that phase. Figure 5: Bipolar Winding. Another common winding is the unipolar winding. This consists of two windings on a pole connected in such a way that when one winding is energized a magnetic north pole is created, when the other winding is energized a south pole is created.
This is referred to as a unipolar winding because the electrical polarity, i.During the hunt for an electric motor for a particular application, duty cycle is routinely brought up as an important factor in determining your final motor selection.
As a rule of thumb, an application is placed in the continuous duty category when 20 or 30 minutes of uninhibited operation is required. This timespan varies with application and can be determined according to its duty rating—a standard your motor manufacturer can help with once the load, torque, speed, and other variables are made known.
To further expand, it is good to note that this continuous duty classification is temperature driven—if the continuous duty cycle is 20 minutes, that means that it takes 20 minutes for your application, under the rated load, to reach maximum functioning temperature. Excessive heat can cause deterioration of various motor components as well as inhibit performance factors such as torque.
Generally speaking, the volume of a motor is proportional to the amount of heat that can be dissipated fan design is also critical for vented motors. As you can probably guess, intermittent duty cycles, are when operation occurs on an interval basis. So basically, intermittent duty applications have less heat to dissipate, which generates space, weight, and cost savings because a smaller sized motor can typically be used.
For example, in an application where a specific speed-torque point is required but the duty cycle is for 6 seconds every minute, a smaller motor may work for the application in comparison to the motor required for continuous operation. As a result, the duty cycle frequently determines the required motor size for a given application. However, duty cycle can often be overlooked, and this is where your manufacturers can help. Manufacturers need to know what your duty cycle is in addition to your power requirements.
Groschopp has a propriety software program that allows us to quickly search specific duty cycles. Narrow your search by selecting motor type, gearbox, voltage, and phase options for your desired motor. Select a dominant variable: choose one of the three parameters to narrow your search. The selected variable determines which slider bar you will be able to manually move. Use the slider corresponding to your dominant variable to further narrow your motor selection.
Duty Cycle: What You Need to Know
The other sliders will automatically move to show available ranges based on the range of your selected variable. Results will upload as your search criteria changes. If you have any questions regarding your results or how to use the search tool, you can chat with us using the green tab on the left-hand side of your screen.
Note: Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search. Selecting the Universal motor type will prompt a message taking you to the Universal product page.
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Motor duty cycle
Contact us at or by email at sales groschopp. You can also chat with us using the green tab on the left side of your screen. Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search. Standard frame sizes and motor features can be found on the Universal page. Selected Products. How did you hear about us?
Continuous Duty During the hunt for an electric motor for a particular application, duty cycle is routinely brought up as an important factor in determining your final motor selection. How to use the Motor Search Tool Narrow your search by selecting motor type, gearbox, voltage, and phase options for your desired motor. Yellow represents selected option. Dark gray represents available options.Here it is. As a purchaser of a motor, you have responsibility to let the manufacturer know the anticipated duty of the motor.
Thermal Equilibrium is the state reached when the temperature rise of the machine does not vary by more than 2K per hour. If you don't specify the duty cycle, the manufacturer will likely assume S1.
Click on the image to see a larger version, illustrating the duty cycles. Steven has over twenty five years experience working on some of the largest construction projects. He has a deep technical understanding of electrical engineering and is keen to share this knowledge. About the author. It starts with me reading one of the Horrible History books with my son Groovy Greeks.
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Loading, please wait.The term duty defines the load cycle to which the machine is subjected, including, if applicable, starting, electric braking, no-load and rest de-energized periods, and including their durations and sequence in time. Duty considered as generic term, for example, can be classified as continuous duty, short-time duty or periodic duty. The percentage ratio between the period of loading and the total duration of the duty cycle is defined cyclic duration factor.
Where the purchaser does not declare the duty, the manufacturer shall assume that duty type S1 continuous running duty applies. The duty type shall be designated by the appropriate abbreviation and the purchaser may describe the type of duty based on the classifications according to the indications given below. In compliance with the classification of Std.
IEC here are some indications regarding the duty types which are typically considered as reference to indicate the rating of the motor. For a motor suitable to this duty type, the rating at which the machine may be operated for an unlimited period is specified. This class of rating corresponds to the duty type whose appropriate abbreviation is S1. For a motor suitable to this duty type, the rating at which the machine, starting at ambient temperature, may be operated for a limited period is specified.
This class of rating corresponds to the duty type whose appropriate abbreviation is S2. A complete designation provides the abbreviation of the duty type followed by an indication of the duration of the duty S2 40 minutes.
For a motor suitable to this duty type, the rating at which the machine may be operated in a sequence of duty cycles is specified. With this type of duty, the loading cycle does not allow the machine to reach thermal equilibrium. The cyclic duration factor is defined as the ratio between the period of loading, including starting and electric braking, and the duration of the duty cycle, expressed as a percentage. The contribution to the temperature-rise given by the starting phase is negligible.
A complete designation refers to the duty type and gives the same type of indication of the previous case. There is no time de-energized and at rest. For a motor suitable to this duty type, the rating at which the machine may be operated non-periodically is specified. This class of rating corresponds to the duty type whose appropriate abbreviation is S9.What is Duty Cycle?
This duty includes frequently appplied overloads which may greatly exceed the reference load. For a motor suitable to this duty type, the rating at which the machine may be operated with a specific number of discrete loads for a sufficient time to allow the machine to reach thermal equilibrium is specified.
The maximum permissible load within one cycle shall take into consideration all parts of the machine the insulation system, bearings or other parts with respect to thermal expansion. This class of rating corresponds to the duty type whose appropriate abbreviation is S The minimum load during a duty cycle may have value zero and be relevant to a no- load or rest condition.