Techniques And Measures For Electromagnetic Compatibility (Emc) - Mitsubishi Electric 800 Series Instruction Manual

NOTE
• Install the earth leakage circuit breaker (ELB) on the input side of the inverter.
• In the
Earthing (Grounding) must conform to the requirements of national and local safety regulations and electrical codes. (NEC
section 250, IEC 61140 class 1 and other applicable standards)
• When the breaker is installed on the output side of the inverter, it may be unnecessarily operated by harmonics even if the
effective value is within the rating.
In this case, do not install the breaker since the eddy current and hysteresis loss will increase, leading to temperature rise.
• The following models and products are standard breakers: the models BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, and
NV-2F, the earth leakage circuit breakers with AA neutral wire open-phase protection, and the earth leakage relays (except
NV-ZHA).
The other series, models, and products are designed for harmonic and surge suppression: the NV-C series, NV-S series, MN
series, the models NV30-FA, NV50-FA, NV-H, and BV-C2, earth leakage alarm breaker NF-Z, and the earth leakage relay NV-
ZHA.
3.1.2 Techniques and measures for electromagnetic
compatibility (EMC)
Some electromagnetic noises enter the inverter to cause the inverter malfunction, and others are radiated by the inverter to
cause the peripheral devices to malfunction. (The former is called EMS problem, the latter is called EMI problem, and both is
called EMC problem.) Though the inverter is designed to be immune to noises, it requires the following basic measures and
EMS measures as it handles low-level signals. Pay attention to the electromagnetic noises that could be generated by the
inverter since the inverter chops outputs at high carrier frequency. If these electromagnetic noises cause peripheral devices to
malfunction, EMI countermeasures should be taken to suppress noises. These techniques differ slightly depending on EMI
paths.
 Basic measures
• Do not run the power cables (I/O cables) and signal cables of the inverter in parallel with each other and do not bundle
them.
• Use shielded twisted pair cables for the detector connecting and control signal cables and connect the sheathes of the
shielded cables to terminal SD.
• Ground (Earth) the inverter, motor, etc. at one point.
 EMS measures to reduce electromagnetic noises that enter the inverter
and cause it to malfunction
When devices that generate many electromagnetic noises (which use magnetic contactors, electromagnetic brakes, many
relays, for example) are installed near the inverter and the inverter may malfunction due to electromagnetic noises, the
following countermeasures must be taken:
• Provide surge suppressors for devices that generate many electromagnetic noises to suppress electromagnetic noises.
• Install data line filters to signal cables (refer to
• Ground (Earth) the shields of the detector connection and control signal cables with cable clamp metal.
92
3. Precautions for Use of the Inverter
3.1 Electro-magnetic interference (EMI) and leakage currents
connection earthed-neutral system, the sensitivity current is blunt against a ground fault in the inverter output side.
page 93).