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132
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G. PERIPHERAL UNIT NOTES
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Installation and selection of molded-case circuit breaker ————————————
On the input power side, a molded case circuit breaker (MCCB) to protect inverter primary wiring should be installed. The inverter
power factor (depending on power voltage, output frequency, and load) must be taken into account for selecting the MCCB. For
standard selection, see page 13. If a full electromagnetic MCCB is to be used, select a larger capacity because the operating
characteristics are altered by harmonic current. A leakage current breaker of inverter use is recommended.
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Use of input side magnetic contactor ————————————————————
The inverter can be used without an input side magnetic contactor (MC). An input MC can be used to prevent an automatic restart
after recovery from an external power loss during remote control operation. However, do not use the MC frequently for start/stop
operation, or it will lead to a reduced reliability. When the digital operator is used, automatic restart after power failure is disabled so
that MC starting is impossible. Although the MC can stop the inverter, regeneration braking is disabled and the motor coasts to stop.
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Use of secondary magnetic contactor ————————————————————
In general, magnetic contactors on the output of the inverter for motor control should not be used. Starting a motor with the inverter
running will cause large surge currents and the inverter overcurrent protector to be triggered. If an MC is used for switching to
commercial power supply, switch MC after the inverter and the motor stop. To switch during motor rotation, use the speed search
function.
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Use of overload relay ———————————————————————————
The inverter includes an electronic thermal protective function to protect the motor from overheating. If more than one motor is driven
with a single inverter or when a multi-pole motor is used, place an overload relay between the inverter and the motor. Set 1 to the first
position of Sn-14 (xxx1), and set the overload relay to the current nameplate value at 50Hz, or 1.1 times of that at 60 Hz.
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Power-factor improvement (elimination of phase advance capacitor) ———————
To improve the power-factor, install an AC reactor on the inverter's primary side. Power-factor improvement capacitors or surge
suppressors on the inverter output side will be damaged by the harmonic component in the inverter output. Also, the overcurrent
caused in the inverter output will trigger the overcurrent protection. To avoid this, do not use capacitors or surge suppressors in the
inverter's output. To improve the power-factor, install an AC reactor on the inverter primary side.
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Radio frequency interference ————————————————————————
Because the inverter I/O (main circuit) contains a higher harmonics component, it may emit RFI noise to communication equipment
(AM radio, etc.) near the inverter. Use a noise filter to decrease the noise. Use of a metallic conduit between the inverter and motor
and grounding the conduit is also effective. Proper routing of input and output leads is also recommended.
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Wire thickness and cable length ———————————————————————
If the inverter is connected to a distant motor, (especially when low frequency is output,) motor torque decreases because of voltage
drop in the cable. Use sufficiently heavy wire.
When a digital operator is to be installed separately from the inverter, use the TECO connection cable (option). For remote control
with analog signals, connect the operating pot or operating signal terminal and the inverter within 30m of the inverter. The cable must
be routed separately from power circuits (main circuit and relay sequence circuit) so that it is not subjected to inductive interference
by other equipment. If frequencies are set not only from the digital operator but also with external frequency controller, use twisted
pair shielded wire as shown in the following figure and connect the shielding to terminal E, not to the ground.
AUX. FREQ. REFERENCE
0 - 10V (20k
Ω
) INPUT
E
+15V
VIN
AIN
AUX
GND
0V.
P
P
P
0V
2k
Ω
0 TO +10V
4 TO 20mA
0 TO +10V
FREQUENCY
CONTROLLER
2k
Ω
SHIELDED INSULATED WIRE
CONNECTION TERMINAL
MASTER SPEED REFERENCE
0 - 10V (20k
Ω
)
MASTER SPEED REFERENCE
4 - 20mA (250
Ω
)
3
2
1
TWISTED PAIR
INSULATED WIRE
SPEED SETTING POWER SUPPLY
+15V 200mA
Содержание 7300PA series
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