Appendix A.
EMC Standard Installation Guide | VFD-ED
A-5
How to prevent EMI
2.1 Types of EMI: Common-mode and differential-mode noise
The electromagnetic noise of an AC motor drive can be distinguished into common-mode and differential-
mode noise. Differential-mode noise is caused by the stray capacitance between the conducting wires and
common-mode noise is caused by the common-mode coupling current path created by the stray capacitance
between the conducting wires and ground.
Basically, differential-mode noise has a greater impact to the AC motor drive and common-mode noise has a
greater impact to high-sensitivity electronic devices. An excessive amount of differential-mode noise may trigger
the circuit protection system of the AC motor drive. Common-mode noise affects peripheral electronic devices via
the common ground connection.
EMC problems can be more serious when the following conditions apply:
When a large horsepower AC motor drive is connected to a large horsepower motor.
The AC motor drive’s operation voltage increases.
Fast switching of the IGBTs.
When a long cable is used to connect the motor to the AC motor drive.
2.2 How does EMI transmit? (Noise transmission path)
Noise disturbs peripheral high-sensitivity electrical devices/systems via conduction and radiation, their
transmission paths are shown hereafter:
1. Noise current in the unshielded power cable is conducted to ground via stray capacitances into a common-
mode voltage. Whether or not other modules are capable to resist this common-mode noise depends on their
Common-Mode Rejection Ratio (CMRR), as shown in the following figure.
Noise
Unshielded cable
Ground
Cstray
Send
Load
Receive
2. Common-mode noise in the power cable is transmitted through the stray capacitance and coupled into the
adjacent signal cable, as shown in Figure 2. Several methods can be applied to reduce the effect of this
common-mode noise; for example, shield the power cable and/or the signal cables, separate the power and
signal cables, take the input and output side of the signal cable and twist them together to balance out the stray
capacitance, let power cables and signal cables cross at 90°, etc.
Summary of Contents for VFD-ED Series
Page 3: ......
Page 10: ...Ch01 Introduction VFD ED 1 3 1 2 Model Name 1 3 Serial Number...
Page 21: ...Ch01 Introduction VFD ED 1 14 Built In Keyboard Panel KPED LE01 Unit mm inch...
Page 26: ...Ch02 Installation VFD ED 2 5 Ambient Temperature Derating Curve Altitude Derating Curve...
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Page 28: ...Ch03 Wiring VFD ED 3 1 Chapter 3 Wiring 3 1 Wiring 3 2 System Wiring Diagram...
Page 30: ...Ch03 Wiring VFD ED 3 3 3 1 Wiring...
Page 32: ...Ch03 Wiring VFD ED 3 5...
Page 38: ...Ch04 Main Circuit Terminals VFD ED 4 3 4 1 Main Circuit Diagram Frame B Frames C D Frame E...
Page 46: ...Ch05 Control Terminals VFD ED 5 3 Frame E Step 1 Step 2 Step 3...
Page 47: ...Ch05 Control Terminals VFD ED 5 4 5 2 Control Terminal Specifications...
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Page 94: ...06 Optional Accessories VFD ED 6 43 EMC Filter Model B84143D0150R127 Unit mm inch...
Page 95: ...06 Optional Accessories VFD ED 6 44 EMC Filter Model B84143D0200R127 Unit mm inch...
Page 96: ...06 Optional Accessories VFD ED 6 45 EMC Filter Model B84142A0042R122 Unit mm inch...
Page 242: ...Ch12 Descriptions of Parameter Settings VFD ED 12 31 Elevator Timing Diagram...
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Page 351: ...Ch16 Safe Torque Off Function VFD ED 16 10 16 5 6 STL1 Figure 6 16 5 7 STL2 Figure 7...
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Page 373: ...Appendix A EMC Standard Installation Guide VFD ED A 20 The page intentionally left blank...
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