Noise Prevention Measures - Mitsubishi Electric MELSERVO-J2S Series Manual

６.２ Noise Prevention Measures
Noises can be either the noise that comes from the outside and causes malfunction to the servo amplifier or the noise
that comes from the servo amplifier and causes malfunction to peripheral modules. Servo amplifiers are the electronic
equipment that operates with weak signals. So, you need several general prevention measures as described below in
this section.
In addition to this, more noises are generated because the output from the servo amplifiers is chopped with high carrier
frequency. If peripheral modules suffer from malfunction, you should provide noise prevention measures. Your measures
may be different depending on the routes of noise transfer.
(1) Noise Prevention Methods
(a) General Prevention Measures
・ Avoid parallel arrangement of the drive line (input/output line) and the signal line of the servo amplifier.
Avoid bundling them, too. Separate them into different wiring arrangement.
・ Use twisted pair shield cables as the connection line with the encoder and as the control signal line. Connect
the external shield to the SD terminal.
・ Use only one grounding point for the servo amplifier, the servomotor, and so forth.
(b) The Noise That Comes from the Outside and Causes Malfunction to the Servo Amplifier
If the servo amplifier is surrounded by several modules that may emit noises (an electromagnetic contactor,
an electromagnetic brake, several relays, and so forth), and if the servo amplifier may suffer from malfunction,
you need to provide such noise prevention measures as described below:
・ Install a surge killer on the module that may emit noises frequently, and suppress noise emissions.
・ Install a data line filter on the signal line.
・ Use a cable clamp metal fitting to ground the shields of the connection line with the encoder and the control
signal line.
・ The servo amplifier has a built-in absorber. Some larger external noises and a lightning surge should be
also prevented to protect the servo amplifier and other modules. We recommend that you provide a varistor
on the power input line of a module.
(c) The Noise That Comes from the Servo Amplifier and Causes Malfunction to Peripheral Modules
Firstly, the noise emitted from the servo amplifier comes from the main part of the servo amplifier or from
the cables that are connected to the main circuit (for input/output) of the servo amplifier. Secondly, the
noise is induced electromagnetically or electrostatically around the signal lines of the peripheral modules
in the vicinity of the main circuit. Thirdly, the noise is transferred by the power supply lines.
サーボアンプの
Noise emitted from the
servo amplifier 発生ノイズ
Airborne noise Noise directly radiated from the servo amplifier
空中伝播ノイズ
Noise radiated from the power supply cable
Noise radiated from the servo motor connection cable
Electromagnetic induction noise Routes ④ and ⑤
電磁誘導ノイズ ...経路④，⑤
Electrostatic induction noise 静電誘導ノイズ Routes ⑥
...経路⑥
Noise transmitted by the cable
電路伝播ノイズ Cable-transmitted noise
Noise returned from the grounding wire caused by electric leak
６-６
6 － 3
サーボアンプからの直接輻射ノイズ
電源線からの輻射ノイズ
サーボモータ接続線からの輻射ノイズ
電源線を伝播するノイズ
漏れ電流による接地線からの回込みノイズ
...経路① Routes ①
Routes ②
...経路②
Routes ③
...経路③
...経路⑦
Routes ⑦
Routes ⑧
...経路⑧