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

NOTE
• Install the earth leakage circuit breaker (ELB) on the input side of the converter.
• 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: BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, NV-2F,
earth leakage relay (except NV-ZHA), NV with AA neutral wire open-phase protection
The other models are designed for harmonic and surge suppression: NV-C/NV-S/MN series, NV30-FA, NV50-FA, BV-C2,
earth leakage alarm breaker (NF-Z), NV-ZHA, and NV-H.
• For the leakage current of a 75 kW or higher motor, contact the motor manufacturer.
3.1.2 Techniques and measures for electromagnetic
compatibility (EMC)
Some electromagnetic noises enter the inverter or the converter unit to cause its malfunction, and others are radiated by the
inverter or the converter unit to cause the peripheral devices to malfunction. Though the inverter or the converter unit is
designed to have high immunity performance, it handles low-level signals, so it requires the following basic techniques. 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 or the converter unit 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 or the converter unit, motor, etc. at one point.
 Techniques to reduce electromagnetic noises that enter and cause a
malfunction of the inverter or the converter unit (EMI countermeasures)
When devices that generate many electromagnetic noises (which use magnetic contactors, electromagnetic brakes, many
relays, for example) are installed near the inverter or the converter unit and it 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
• Ground (Earth) the shields of the detector connection and control signal cables with cable clamp metal.
78
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 79) to signal cables.