How Many Meters Can the Motor and Control Pack of a Speed Control Motor Be Separated From Each Other?
This is the demo unit on display in the showroom, and I'm thinking of changing the part of the mechanism where the speed control motor is used. The torque is OK with the current motor, but I need to extend the distance between the motor and the driver to reach it. How many meters could it be extended?
Good idea. The extension distance varies depends on the product, so it's hard to generalize, but that demo unit on display is the BMU Series connector type. 10 meters would be the maximum extension distance.
I want to extend it by 1 m, so that's fine! But what happens if it's more than 10 m?
As the extension distance increases, the resistance of the lead wire increase and it will affect the voltage drop. That means that less current will flow through the motor, which would lower the output torque. Also, the longer you extend it, it will be more susceptible to noise. It's also possible that it could malfunction in the wrong operating environment.
Is that so? So it's not good to be too long.
That’s right. Also, when extending it, you need to be careful about the AWG of the motor lead wire.
AWG?? What is that?
AWG is an acronym for American Wiring Gage! This defines the core wire configuration and conductor cross-sectional area of lead wire. It is called by AWG No. and the larger the number, the cross sectional area of the lead wire will be smaller and the wire will be thinner.
AWG No.
Lead wire cross sectional area (mm2)
26
0.128
24
0.205
22
0.325
20
0.519
I see. But what does that have to do with extending the lead wire?
If the cross sectional area of the lead wire is small, the resistance will increase, so it's harder for the current to flow, which could result in a lower output torque. So, if you're going to extend it, it's better to use the same AWG as the one listed on the motor lead wire, or the one that is thicker. This is an important point that can also be applied to other motors, such as stepper motors.
There are also such points to note. Then I need to prepare the lead wire. Let's see...
Each speed control motor has its own extension cable. When using this cable, the AWG is also the same, so it can be used without any problem within the respective extension distances under normal circumstances, and with the BMU Series, it's easy to make a 1-touch connection between the motor and driver with the connector.
Oh, that’s true. For BMU Series, there are extension cables available up to 10 m! With this, length is enough and wiring will be simple, which is great. Can I use a cable other than this one to extend the length?
For products like the BMU Series that have a connector on the end of the cable, you can't extend the cable with anything other than the specified cable. But we have several different lengths to accommodate the customer's needs. By the way, products with lead wires coming out of the motor can be extended with other cables, but you need to be careful about the point I mentioned earlier.
The point is about noise and AWG!
▲Twisted-Pair Wire
That’s right. In particular, signal lines such as the tachogenerator wire of a speed control motor are more susceptible to the effects of noise the longer the extension distance. It is recommended that you keep the distance within 10 meters as much as possible. It would be better if the signal lines of any motor, not just tachogenerator lines, could be separated from other power lines and motor power lines, or if they could be twisted-pair wire (▲), or if shielded wire could be used as protection against noise. Composite cables are convenient because they use twisted-pair wires for signal lines and they are shielded. And of course the BMU Series extension cables are also shielded!
I see! I’ve got it now. Well then, I will start modifying the demo unit right away!!
* The extension cable and maximum extension distance vary depending on the Series.
