Oriental motor BLH Series - Noise Measures

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Connection
6.9 Noise measures
There are two types of electrical noises: One is a noise to invade into the driver from the outside and cause the driver
malfunction, and the other is a noise to emit from the driver and cause peripheral equipments malfunction.
For the noise that is invaded from the outside, take measures to prevent the driver malfunction. It is needed to take
adequate measures because signal lines are very likely to be aected by the noise.
For the noise that is emitted from the driver, take measures to suppress it.
Measures against electrical noise
There are the following three methods mainly to take measures against the electrical noise.
z
Noise suppression
•
When relays or electromagnetic switches are used, use noise lters or CR circuits to suppress surge generated by
them.
•
Use a connection cable (sold separately) when extending the wiring distance between the motor and the driver.
This is eective in suppressing the electrical noise emitted from the motor.
•
Cover the driver by a metal plate such as aluminum. This is eective in shielding the electrical noise emitted from the
driver.
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Prevention of noise propagation
•
Separate power lines such as motor cable and power supply cable from signal lines for a distance of 100 mm (3.94 in.)
or more, and also do not bundle them or wire them in parallel. If the power lines must cross over the signal lines, wire
them at right angles.
•
Use a cable of AWG26 (0.14 mm
2
) or thicker for the signal cable of the driver, and keep the wiring distance of 3 m (9.8ft.)
or less.
•
For more eective elimination of noise, use shielded cables for a power supply cable and I/O signal cable, or attach
ferrite cores if non-shielded cables are used.
•
Keep cables as short as possible without coiling and bundling extra lengths.
•
To ground a shielded cable, use a metal cable clamp that can
maintain contact with the entire circumference of the shielded
cable, and ground as near the product as possible.
Cable cramp
Shielded cable
•
Grounding multiple points will increase eect to block electrical noise because impedance on the grounding points is
decreased.
However, ground them so that a potential dierence does not occur among the grounding points.
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Suppression of eect by noise propagation
•
Loop the noise propagated cable around a ferrite core. Doing so will prevent the propagated noise invades into the
driver or emits from the driver. The frequency band in which an eect by the ferrite core can be seen is generally
1 MHz or more. Check the frequency characteristics of the ferrite core used. When increasing the eect of noise
attenuation by the ferrite core, loop the cable a lot.