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Installing and selecting MCCB
Install a molded case circuit breaker (MCCB) on the power receiving side to protect the wiring at the inverter input side. Select
an MCCB according to the inverter input side power factor, which depends on the power supply voltage, output frequency and
load. Especially for a completely electromagnetic MCCB, a slightly large capacity must be selected since its operation
characteristic varies with harmonic currents. (Check it in the data of the corresponding breaker.) As an earth leakage current
breaker, use the earth leakage current breaker designed for harmonics and surge suppression.
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
(page
• Ground (Earth) the shields of the detector connection and control signal cables with cable clamp metal.
72) to signal cables.
3. PRECAUTIONS FOR USE OF THE INVERTER
3.1 Electro-magnetic interference (EMI) and leakage currents
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