Can reversible motors only be used for 30 minutes?

Q: It's really hot today, but it's so nice to come and play in the haunted house with you!
A: You startled me, be careful not to flash it to your waist!
Q: Ah! I'm scared to death. Hey, take a closer look at this ghost, it's using a reversible motor to run out and scare people!
A: Oh! You are quite clear about it.
Q: Ah! The motor feels very hot to the touch! Is it due to prolonged physical activity?
A: Do you know what a reversible motor is? Tell me.
Q: Of course I know! The so-called reversible motor is a motor that can instantly switch between forward and reverse rotation, suitable for use in situations where repeated operation and stopping are required.
A: Yes! Good learning.
Q: By the way! Isn't it written in the catalog that reversible motors are rated for 30 minutes? Does it mean it can only take 30 minutes?
A: Well, if a reversible motor is used for continuous operation in the same direction as an induction motor, it can only be used for 30 minutes!
Q: Why is that?
A: This is related to the characteristics of reversible motors. The so-called reversible motor is designed to achieve the function of instantaneous forward and reverse rotation. Therefore, compared with induction motor, the current passing through during operation is more and the temperature is more likely to rise. That's why it is recommended that customers use reversible motor for continuous operation for 30 minutes!
Q: So that's how it is.
A: However, if the temperature can be avoided from rising too quickly, the usage time can be further extended! Generally speaking, if the temperature of the motor casing remains below 90 degrees, it can operate for more than 30 minutes. Although it is best to use at temperatures below 90 degrees, the lifespan of the motor still depends on the temperature. Of course, it would be best if it could operate at low temperatures.
Q: Is there any way to avoid motor temperature rise?
A: The temperature of the motor may vary due to various factors such as load, operating cycle, motor installation method, and surrounding environment. Therefore, methods such as directly cooling the motor, installing heat dissipation plates, or reducing the motor's operating time to allow it to cool naturally can all prevent the motor from rising too quickly and increase its service life.
Q: I see, I understand. Although reversible motors are rated for 30 minutes, as long as you pay attention to the temperature changes in the motor casing, they can still operate continuously for more than 30 minutes. I learned so much today!
A: Be careful!
Q: Hmm? Wow

Does noise also have certain rules?

Q: The road ahead is under renovation and has been noisy all day, making it impossible to work.
A: Yes. This is called 'noise'.
Q: But if you close the window, the office will become very stuffy.
A: You might as well borrow the fan in the showroom to dissipate heat. (laughs)
Q: You bullied me again. By the way! The so-called noise, in the series of fans published in the comprehensive catalog, seems to mention the noise value.
A: Yes, fans have a wide range of uses. Not only factories, offices, and hospitals use fans, so noise levels are also considered when selecting them! Speaking of noise level, it refers to the value measured in the A-band within a distance of 1 meter from the side where the fan sucks in air.
Q: Huh~What is the frequency band?
A: Since the human ear can hear sounds with frequencies between 20Hz and 20kHz, the noise level is close to the range that humans can hear, which is the A-band.
Q: I don't even know! Does the noise from road construction belong to the A band?
A: Well, the noise level of a typical road construction project is about 110 decibels. By the way! The fan produced by Dongfang Motor is about 40 decibels, which is equivalent to the sound in a quiet park!
Q: Hmm~But the sound heard in different places is different in size!
A: Yes! Depending on the distance of the test, the noise level will also vary, so we will definitely clearly indicate the test distance in meters on our catalog!
Q: Really! This is indeed a value measured at a distance of 1 meter from the air intake side of the fan.
A: Different distances are measured, and the values obtained will also change. When comparing, it is important to first confirm how far the measured distance is!
Q: I think although a low decibel value means a low noise level, is it allowed to measure at a slightly farther distance?
A: So it's important to pay attention to the distance being measured. There are certain rules regarding the noise level and distance. For example, if the measurement distance is extended from 1 meter to 2 meters, the noise level will decrease by 6 decibels; Extending to 4 meters will reduce the noise level by 6 decibels, for a total reduction of 12 decibels. On the contrary, if the measurement distance is shortened from 1 meter to 50 centimeters, the noise level will increase by 6 decibels!
Q: Hmm~So as long as you know the noise level generated within a certain distance, you can calculate the noise level at different distances!
A: Yes.
Q: I understand now! Try to calculate now!
A: It seems like the sound of road repairs has stopped unconsciously while chatting with you.
Q: (Gollum Gollum~)
A: The sound of a stomach growl should be 30 decibels!
Q: It's already noon! Of course, my stomach should growl! What are you going to eat today?

The larger the reduction ratio, the greater the output torque?

Q: How heavy~How heavy~Ah!
A: Move it up quickly!
Q: This thing is really heavy. Isn't it enough to use a conveyor belt? By using a gearbox to increase torque, it is easy to transport goods, isn't it? By the way! Is it true that the larger the reduction ratio, the greater the output torque?
A: Yes.
Q: The allowable torque algorithm for installing the gearbox is... TG=TM × I × η
Allowable torque of the output shaft of the gearbox
TM motor torque
Reduction ratio of I gearbox
Communication efficiency
For example, the combination of the world standard K-series induction motor "4IK25GN-AWU" and the gearbox "4GN180K" is: TM: 205mN · m/η: 66%
So, when these numbers are inserted into the formula, it is:
TG=0.205×180×0.66=24.354 N⋅mTG​=0.205×180×0.66=24.354N⋅m
That is to say, the higher the reduction ratio of the gearbox, the higher its torque can be!
A: Yes, but torque cannot just be calculated by formulas! Actually, it depends on the maximum allowable torque of the gearbox, and there is still an upper limit to the load torque it can withstand!
Q: Is that so?
A: Because the reducer is composed of components such as gears and bearings, it is affected by material and size, and has mechanical strength limitations. Therefore, the allowable torque cannot exceed the limit of mechanical strength!
Q: Well, what would happen if it were used in situations where the maximum allowable torque is exceeded?
A: According to the design of the reducer, the mechanical strength is about 1.5 to 3 times the maximum allowable torque, so a brief overload will hardly cause damage, but it will shorten the service life due to frequency and time of use! So it is not recommended for customers to use it beyond the maximum allowable torque!
Q: So that's right, which means the maximum allowable torque for the combination of "4IK25GN-AWU" and "4GN180K" is 8.0N · m. Only when used within this range can the motor achieve its maximum efficiency.
A: That's right! What should I do if I need a larger torque?
Q: If considering the maximum allowable torque of the gearbox, I think using the high-strength and long-life V series ※ (6W~60W) is a good method. For example, for the same 25W model, if using the V series ※, the maximum allowable torque can reach 16N · m! If the selected torque is insufficient, there are also BH series 200W models available for selection. When installing the reducer, the maximum corresponding torque can reach 70N · m!
A: It's really rare that you put in a lot of effort! But you still missed one! The high-strength FR series ※ is adopted, and the maximum allowable torque of the 90W output power model can also reach 68N · m. It is used in combination with a brushless motor and can also be adjusted in speed!
Q: Yes, the FR series is also a good choice. Oh, speaking of which, aren't you going to use a conveyor belt to transport goods? I don't want to move quickly yet!

What is the maximum distance that can be extended between the motor unit of the speed regulating motor and the speed regulator?

Q: I would like to make some changes to the speed control motor mechanism on the display machine in the motor display area. The current torque of the motor should not be a problem, but the cable between the motor and the governor needs to be extended. May I ask how many meters it can be extended to?
A: Hmm... it depends on the motor used and cannot be generalized. That display machine is using the AXU series, right! The maximum extension distance should be 10.5 meters.
Q: I only need to extend by 1 meter, that's definitely not a problem. But I want to know, what if the extension distance exceeds 10.5 meters?
A: The longer the extension distance, the higher the resistance of the wire will increase, causing a decrease in voltage. That is to say, the decrease in current through the motor causes a decrease in torque. In addition, the longer the extension distance, the more susceptible it is to noise interference. If the usage environment is poor, it may cause motor misoperation.
Q: I see. That means it's not good to extend the distance too long, right?
A: Yes. Additionally, when extending, pay attention to the AWG of the motor wires.
Q: AWG? What is this again?
A: AWG is the abbreviation for American Wiring Gage, which refers to the code for the composition of the wire core and the cross-sectional area of the conductor. It is generally called AWG No. The larger the number, the smaller the cross-sectional area of the wire and the thinner the wire.
Q: Oh, that's right. So what does this have to do with the extension distance of the wire?
A: The smaller the cross-sectional area of the wire, the greater the resistance, making it difficult for current to pass through, resulting in a decrease in torque. So, when extending, the same AWG number wire as recorded on the motor wire should be used or a thicker wire should be used. This is also a key point to pay attention to for other motors such as stepper motors.
Q: So there are still such precautions. So, next I have to prepare the wires. Hmm? Which type of wire is good to use?
A: There are various extension cables for speed regulating motors in the selection of accessories! If the cable with optional accessories is used, as the AWG is the same, there will be no problem as long as it is used in a normal environment and within the specified extension distance range. For the AXU series, the One Touch connector is used between the motor and the governor, which makes it even simpler.
Q: Ah! That's really the case! The AXU series has an extension cable with a length of 10m. Not only is the length sufficient, but the wiring is also simple, it's really great! By the way, if I use cables other than optional accessories, can they also be extended?
A: Products like AXU series cables with connectors at the front end cannot be extended if cables other than optional accessories are used. So we have prepared several lengths of cables to meet the needs of users. Also, for products like the SC series speed regulating motor with bare wire type wires, extension can be done even without using optional accessory cables. However, attention must be paid to the several points I just explained.
Q: It's noise and AWG, right!
A: Yes. Especially for signal lines such as speed control motor generator wires, the longer the extension distance, the more susceptible they are to noise interference. Therefore, it is recommended to control the extension distance within 10m. In addition, it would be better if not only the speed generator wires, but also all Mazda could adopt measures such as separating the power line from the motor power line or using twisted pair wires, shielded wires, etc. For example, when selecting various series of specialized cables for accessories, the signal line uses twisted pair and has been shielded, making it very convenient. It goes without saying that the extension cables of the AXU series have also undergone shielding treatment.
Q: I see! I finally understand. Okay, then I'll go and change the display machine right away. Thank you, goodbye!!

Why is' inertia 'very important when choosing a motor?

Q: Although the wheels of this bicycle are so big, the pedals are so light. It runs so fast!
A: This is because the wheels of this bicycle are designed to be relatively thin according to racing specifications, reducing inertia, which is why it runs so fast!
Q: Is inertia proportional to weight?
A: That's right, but it's not just that!
Q: What else is there?
A: It is also directly proportional to the square of the radius!
Q: I see. When the umbrella is opened and rotated, it feels heavier compared to when it is retracted, and that's exactly why.
A: So, you should understand the impact of inertia when choosing a motor, right?
Q: Hmm? Will it affect the acceleration and deceleration torque that occurs during starting and deceleration?
A: Yes! The greater the inertia, the more proportional the acceleration and deceleration torque will be. What else do you remember?
Q: Is there anything else?
A: You still need to study hard! We also need to consider the allowable inertia and inertia ratio!
Q: Ah! I remember it. When selecting an AC motor, it is also important to note that the allowable inertia of the reducer must exceed the inertia of the equipment (i.e. the load inertia). If the inertia of the load exceeds the inertia of the gearbox, the gearbox will not be able to withstand it and may be damaged.
A: Do you remember last week when you were playing with an umbrella and the umbrella frame broke because you couldn't withstand the acceleration and deceleration torque of inertia? What would happen if it were a stepper motor?
Q: Remember that for a stepper motor, the inertia ratio between the rotor inertia and the load inertia can be calculated using the formula "inertia ratio=load inertia ÷ rotor inertia", and the motor must be selected based on the condition that the inertia ratio is less than 10 times (less than 30 times in α STEP)! But why do we need to consider inertia ratio?
A: This is because even if there is a certain margin of acceleration and deceleration torque, if the inertia ratio is too large, it will not be able to keep up with the acceleration command and cause stepping loss.
Q: Should servo motors and brushless speed regulating motors be selected based on the condition that the allowable inertia (i.e. applicable load inertia) must exceed the load inertia?
A: Yes! If the allowable inertia (i.e. applicable inertia) is exceeded, reliable control cannot be achieved, resulting in unstable motion, warning output, and motor stoppage.
Q: So, as long as a reducer is used to reduce speed, even with a small motor, it can still drive loads with high inertia, right?
A: Oh, you finally have an epiphany! As long as we consider according to the "allowable inertia (applicable load inertia) x reduction ratio ²", it means that we can drive a load equal to the square of the reduction ratio. If your bicycle only needs to slow down by half, it can withstand a load equivalent to the second power of the reduction ratio, which is 4 times the load. How about it? Can I hand over my luggage to you?
Q: In this way, won't my speed be reduced by half? I'm not so stupid yet!

Could you please tell me what the warning circuit for a fan is?

Q: I am checking if the display machine in the showroom is functioning properly. Oh, that's great! The cooling fan is also fine. But I would like to ask, because this is a display room and the fans are installed in prominent positions, it is also very convenient to check. But if installed in a completely invisible place or far away, it can be troublesome to check. Do you know any simple inspection methods?
A: This time you've hit the nail on the head. In fact, it is impossible for all devices to be set up in places where people are present. If this situation occurs, it is recommended to use a fan with a warning circuit.
Q: Warning circuit? Is it the kind of circuit that outputs a warning signal when the fan stops?
A: Not only that! There are many types of warning circuits for fans.
Q: Is that true?
A: Taking OM's fan products as an example, there are three types: speed drop detection type (non-contact/contact), stop detection type, and pulse detector output circuit type, and each product has different warning methods.
Q: There are so many gods! Then I won't be able to figure it out again! How should we use them separately?
A: It depends on under what circumstances you need the fan to output a warning signal.
Q: Oh, so it's still so complicated!
A: For example, if the fan speed decreases and causes equipment failure, it is recommended to use the "speed drop detection type". If it is a situation that can be handled after the fan stops, then the "stop detection type" is more suitable; The "pulse detector output circuit type" is suitable for monitoring the speed of the fan. Because the speed of the fan can be determined based on the number of output pulses, and any abnormalities in the fan can be detected in a timely manner. So, if it belongs to a situation where a slight decrease in speed will have a significant impact on the equipment, it is recommended to use this "pulse detector output circuit type".
Q: I see, there are actually so many types.
A: For example, the "speed reduction type" is detected and alerted by an external applied voltage and through the ON/OFF of an internal circuit. Taking the MRS series 250mm large high static pressure fan as an example, it is ON (open collector output: L level) when rotating normally, and OFF (open collector output: H level) when rotating back.
Q: Oh, do the other two circuits also use the same principle to detect warnings?
A: From the perspective that all three circuits are externally applied with voltage, although they are the same, there are slight differences due to differences in product and warning circuit types. Please double check your respective specifications.
Q: I understand now. As long as I use the warning output function, I don't have to check every day anymore. And if the fan blade gets stuck and stops, it can be immediately detected, so you can feel at ease now.

May I ask what an overheat protector is?

Q: A customer just inquired about the sudden stop of a running motor. The world standard K series 25W induction motor used by the customer should not suddenly stop running.
A: That's right. Induction motors are marked with continuous ratings in the product catalog. Indicates that it can operate continuously for 24 hours. Usually, the motor does not stop when operating within the specified torque range.
Q: How about this. By the way, the customer said, "The device accidentally caught a foreign object and the motor shaft got stuck
A: That's probably the reason! Do you know that in the world standard K series, there is an overheat protection device for motors above 15W.
Q:?
A: In the product catalog, the product name is preceded by a symbol indicating that there is an overheat protection device installed in the Mazda. For the 6W motor (world standard K series), an impedance protection type overheat protection method is adopted.
Q: What is overheat protection?
A: This is an overheat protection device installed inside the motor. When the motor coil exceeds a certain temperature, it will automatically cut off the contact and stop the operation of the motor.
Q: Is that so? What is the function of the overheat protection device?
A: When the motor gets stuck due to overload or other reasons, the surrounding temperature rises sharply, or for some reason, the load increases, causing the temperature of the motor to rise sharply. If this situation is not addressed, the insulation performance inside the motor will deteriorate, resulting in a shortened motor life or the possibility of burning out the coil. An overheat protection device was installed to protect the motor in this situation. Motors that meet foreign safety standards must be equipped with overheat protection devices.
Q: So that's how it is. The protective function of preventing the motor from burning due to heat generation. Just now, it was mentioned that the overheat protection device will activate after exceeding a certain temperature. Under what temperature conditions will the overheat protection device activate?
A: In the specifications of the world standard K series, when the temperature of the coil inside the motor reaches 130 ℃± 5 ℃, the contact is automatically cut off, the temperature drops, and the contact is reconnected at 77 ℃± 15 ℃. However, depending on different models, some temperatures may vary. For detailed information, please confirm the specifications of the overheat protection devices for each motor.
Q: Okay.
A: Did you just mention that the customer had a problem with the motor shaft getting stuck! It is speculated that the motor may have abnormally heated up due to overload, thus exceeding a certain temperature.
Q: Indeed, it is very likely. However, if the motor is in a stopped state for a certain period of time, the temperature will naturally decrease. So after the contact is cut off and the motor stops, won't it automatically resume operation?
A: Yes. But some customers do not want automatic resumption of operation. For this situation, the electronic brake SB50 can be used in conjunction. The SB50 is equipped with an overheat protection switch detection function, which will not automatically resume operation, so it can be used with peace of mind. The overheat protection switch detection function of SB50 will output a warning signal when the motor's overheat protection is started but stopped, so this signal can also be used.
Q: Understood.
A: You can now make suggestions to this client, right!
Q: Okay, I'll tell the client right away!

What is' regenerated electricity '?

Q:!!
A: Oh, it's you! You look different, did you change your hairstyle or something?
Q: As expected, you can tell right away. In April, it will be my second year in the company, so I must work harder... Alright, let's not talk about hairstyles for now, I have to ask for advice again. A customer asked me, "Is there a motor that can control the speed when running in the up and down directions?" Which type of motor should I recommend?
A: What are your own thoughts?
Q: When the power is cut off, the output shaft of the electromagnetic brake motor with no excitation actuation will be mechanically restrained, right. So, does it mean that all speed control motors with electromagnetic brakes can be controlled for speed during up and down operation?
A: Not necessarily. Firstly, when selecting a motor, consider the direction of handling the customer's work first. Due to the different directions of handling work items, the motors used will be different! Let's take a look at the following two situations together.
Figure A: Drive direction upwards (roll up operation)
Figure B: Drive direction facing downwards (roll down operation/regeneration operation)
Q: Oh, that's right!
A: There are many motors that can control the speed when running on the roll, but there are not many motors that can control the speed when running off the roll. It is generally recommended to use DC brushless motors BX series/BHF series.
Q: Why can't other speed regulating motors do it?
A: This is because other speed regulating motors adjust their speed by controlling the voltage phase. That is to say, when the speed decreases, the input current of the motor will increase, and when the speed increases, the input current of the motor will decrease. Adjust the operating speed in this way. However, during the rolling operation, due to the influence of gravity, the motor will actually run at a faster speed according to this set value. Therefore, except for the two series of motors I just recommended, most speed regulating motors will make a judgment that the motor is running faster than the set speed, and automatically reduce the input current of the motor. Think about it, what would happen to the work object in this way?
Q: What will happen? Let me think... Since the motor is driven by gravity, even if the current is reduced, it will not slow down... That is to say, the motor will be in a state where almost no voltage is applied. In this case, the output shaft will be in a FREE state, and the workpiece will fall off?
A: Yes, that's right! But the DC brushless motor can be used for rewinding operation. This is due to differences in construction. Do you know the structure of DC brushless motors?
Q: The DC brushless motor uses permanent magnets on the rotor to turn the stator into an electromagnet, which rotates the rotor through the alternation of N and S poles!
A: That's right! That is to say, DC brushless motors maintain the set speed by switching the polarity of the stator's electromagnet. So, stable speed control can also be achieved during the rolling operation. However, during the rolling operation, the output shaft of the motor will be driven to some extent due to the influence of gravity. At this point, the permanent magnet of the rotor will become a generator, causing the motor to generate reverse voltage and recoil onto the driver. At this time, the electricity is called "regenerative power". If a drive without the ability to absorb "regenerative power" is used for unwinding, it will cause damage to the drive.
Q: I see. That is to say, the BX series of DC brushless motors has the ability to absorb regenerated electricity!
A: Yes! But to absorb regenerated electricity, it is necessary to use the regenerator in the optional accessories. As long as a regenerator is installed, the regenerated electricity can be converted into heat and released. However, there are certain limitations to the release capacity, so it is necessary to calculate the amount of regenerative power that will occur based on values such as torque, revolutions, operating time, and operating cycle.
Q: How about this! Although customers can also calculate the approximate regenerated electricity through calculation formulas, we also provide free calculation services as long as they call us.
A: Yes, that way customers don't have to trouble themselves with calculating.
Q: Alright, then I will immediately confirm the torque, speed, and operating cycle with the customer.