Electro-magnetic interference (EMI) and leakage currents
62
PRECAUTIONS FOR USE OF THE CONVERTER UNIT
400 V class (input power condition: 440 V/60 Hz, power supply unbalance within 3%)
NOTE
• Install the earth leakage circuit breaker (ELB) on the input side of the converter unit.
• In the connection earthed-neutral system, the sensitivity current is blunt against a ground fault at the output side of the
inverter. Earthing (Grounding) must conform to the requirements of national and local safety regulations and electrical codes.
(NEC section 250, IEC 536 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 are standard breakers....... BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, NV-2F
earth leakage relay (except NV-ZHA), and 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 motor leakage current, contact the motor manufacturer.
3.1.2
Countermeasures against EMI generated by the
inverter or the converter unit
Some electromagnetic noises enter the inverter or the converter unit to cause the inverter or the converter unit 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. Also, since the inverter chops outputs at high carrier frequency, that could generate
electromagnetic noises. 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 techniques
- 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, 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 the inverter or the converter unit 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.
- Ground (Earth) the shields of the detector connection and control signal cables with cable clamp metal.
EMC filter
ON
OFF
Wye connection / Delta connection
37
3
(mA)
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