Leakage Currents; Harmonic Suppression Guideline - Mitsubishi Electric FR-E700EX Manual

Leakage currents

Capacitances exist between the drive unit I/O cables, other cables and
earth and in the motor, through which a leakage current flows.
Therefore, take the following measures. Select the earth leakage
current breaker according to its rated sensitivity current, independently
of the carrier frequency setting. (Refer to page 44)
To-earth (ground) leakage currents
Type Influence and Measures
• Leakage currents may flow not only into the drive unit's
own line but also into the other line through the earth
(ground) cable, etc. These leakage currents may
operate earth (ground) leakage circuit breakers and
earth leakage relays unnecessarily.
Countermeasures
• Use an earth leakage circuit breaker with a weak
sensitivity in a high frequency range.
The output current of the drive unit contains a high-
Influence and
frequency leakage current component, which gives
measures
relatively low impacts to human bodies. The detention
level for this high-frequency leakage current
component can be set weaker to prevent unnecessary
operations.
• Minimize the stray capacitance between the earth.
Use the cables insulated with low dielectric constant
material, and perform wiring to make the wiring length
between the drive unit and the motor to be as short as
possible.
NV1
Power
supply
Undesirable
Leakage
breaker
current path
NV2
Leakage
breaker
Line leakage current
Type Influence and Measures
• This leakage current flows via a static capacitance
between the drive unit output cables.
• The external thermal relay may be operated
unnecessarily by the harmonics of the leakage current.
Influence and
Countermeasures
measures • Use Pr.9 Electronic thermal O/L relay
• To ensure that the motor is protected against line-to-
line leakage currents, it is recommended to use a
temperature sensor to directly detect motor
temperature.
MCCB MC
Undesirable
Power
supply
current path
Harmonic suppression guideline
Harmonic currents flow from the drive unit to a power receiving point
via a power transformer. The harmonic suppression guideline was
established to protect other consumers from these outgoing harmonic
currents.
"Harmonic suppression guideline for consumers who receive high
•
voltage or special high voltage"
This guideline sets forth the maximum values of harmonic currents
outgoing from a high-voltage or especially high-voltage consumer
who will install, add or renew harmonic generating equipment. If any
of the maximum values is exceeded, this guideline requires that
consumer to take certain suppression measures.
Drive unit
Motor
C
C
Motor
C
Thermal relay
Motor
Drive
M
unit
Line-to-line static
capacitances
Line-to-line leakage currents path
Users who use models other than the target models are not covered
by the guideline. However, we ask to connect an AC reactor or a DC
reactor as before to the users who are not covered by the guideline.
For compliance to the harmonic suppression guideline for
consumers who receive high voltage or special high voltage
Input
Target
Power
Capacity
Supply
Make a judgment based on "Harmonic
suppression guideline for consumers who
receive high voltage or special high voltage"
issued by the Japanese Ministry of Economy,
Trade and Industry (formerly Ministry of
International Trade and Industry) in September
1994 and take measures if necessary. For
calculation method of power supply harmonics,
Three- refer to materials below.
All
phase Reference materials
capacities
200V • "Harmonic suppression measures of the
inverter" Jan. 2004 Japan Electrical
Manufacturer's Association
• "Calculation method of harmonic current of
the general-purpose inverter used by specific
consumers" JEM-TR201 (revised in Dec.
2003): Japan Electrical Manufacturer's
Association Japan Electrical Manufacturer's
Association
For compliance to "Harmonic
transistorized inverter (input current of 20A or less) for consumers
other than specific consumers" published by JEMA.
Connect the AC reactor or DC reactor recommended in a catalog or an
instruction manual.
Reference materials
• "Harmonic suppression guideline of the general-purpose inverter
(input current of 20A or less)" JEM-TR226 (revised in Dec. 2003):
Japan Electrical Manufacturer's Association
Calculation of outgoing harmonic current
Outgoing harmonic current = fundamental wave current (value converted
from received power voltage)  operation ratio  harmonic content
•Operation ratio: Operation ratio = actual load factor operation time
•Harmonic content: Found in Table.
Table 1: Harmonic Contents (Values at the fundamental current of 100%)
Reactor 5th 7th 11th 13th 17th 19th 23rd 25th
Three- Not used 65 41
Used (AC side) 38 14.5 7.4
phase
Used (DC side) 30 13
bridge
Used
(Capacitor
28 9.1
(AC, DC sides)
smoothing)
Table 2: Rated Capacities and Outgoing Harmonic Currents for Three-
phase Drive Unit Drive
Outgoing Harmonic Current Converted from 6.6kV (mA)
(No reactor, 100% operation ratio)
200V 5th 7th
0.1 0.61 18 0.22 11.7 7.38 1.53 1.386 0.774 0.558 0.468 0.324
0.2 0.98 30 0.35 19.5 12.3 2.55 2.31 1.29 0.93 0.78 0.54
0.4 1.61 49 0.57 31.85 20.09 4.165 3.773 2.107 1.519 1.274 0.882
0.75 2.74 83 0.97 53.95 34.03 7.055 6.391 3.569 2.573 2.158 1.494
Countermeasures
suppression guideline of the
ratio during 30 minutes
8.5 7.7 4.3 3.1 2.6 1.8
3.4 3.2 1.9 1.7 1.3
8.4 5.0 4.7 3.2 3.0 2.2
7.2 4.1 3.2 2.4 1.6 1.4
11th 13th 17th 19th 23rd 25th
48