Omron VARISPEED E7 User Manual page 52

Installing a Thermal Overload Relay Contact for Motor Protection
This Inverter has an electronic thermal protection function to protect the motor from overheating. If, however,
more than one motor is operated with one Inverter or a multi-polar motor is used, always install a thermal
relay (THR) between the Inverter and the motor and set L1-01 to 0 (no motor protection). The control circuit
should be designed so that the contacts of the thermal overload relay turn OFF the magnetic contactor on the
main circuit inputs.
Cable Length between Inverter and Motor
If the cable between the Inverter and the motor is long, the high-frequency leakage current will increase, caus-
ing the Inverter output current to increase as well. This may affect peripheral devices. To prevent this, adjust
the carrier frequency (set in C6-02) as shown in
Cable length
Carrier frequency
Ground Wiring
Observe the following precautions when wiring the ground line.
Always use the ground terminal of the 200 V Inverter with a ground resistance of less than 100 Ω and that
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of the 400 V Inverter with a ground resistance of less than 10 Ω.
Do not share the ground wire with other devices, such as welding machines or power tools.
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Always use a ground wire that complies with technical standards on electrical equipment and minimize the
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length of the ground wire.
Leakage current flows through the Inverter. Therefore, if the distance between the ground electrode and
the ground terminal is too long, potential on the ground terminal of the Inverter will become unstable.
When using more than one Inverter, be careful not to loop the ground wire.
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OK
Connecting a Braking Unit (CDBR) and a Braking Resistor Unit (LKEB)
Connect a Braking Unit and a Braking Resistor Unit to the Inverter as shown in the
L3-04 (Stall prevention selection during deceleration)
(Select either of them.)
The Braking Resistor Unit will not work if L3-04 is set to 1 (i.e., if stall prevention is enabled for decelera-
tion). Hence the deceleration time may be longer than the set time (C1-02/04).
To prevent the braking unit/braking resistor unit from overheating, design the control circuit to turn OFF the
inverter output using the thermal overload relay contacts of the Unit as shown in
Table 2.6. (For details, refer to
Table 2.6 Cable Length between Inverter and Motor
50 m max.
15 kHz max.
NO
Fig 2.6 Ground Wiring
0 (Disable stall prevention function)
Chapter 5, User
100 m max. More than 100 m
10 kHz max. 5 kHz max.
Fig 2.7.
Fig 2.7.
2
Parameters.)
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