Toshiba Tosvert VF-A5 - Manual (Page 19)

Note) In this case, ensure that S4 is set to 'Emergency
stop function", by setting | /h H [in
0 r. 5 h to ID.
If the Th-Ry functions, the inverter will display
• E ', and fault trip.
* Other unused terminals can also be used instead of the S4
terminal.
Fig. 5.3 Wiring example using external thermal relays
C r. 51 etc., indicate the LED display on the operation panel. (Refer to Appendix 3, Character
codes, on page 123. The boxed items indicate a parameter or panel operation key.
(
2
)
( 3 )
When using the VF-A5 to drive a Toshiba VF motor*, designed exclusively for constant torque/inverter-
driven applications, set the electronic thermal protection characteristics for a VF motor.
(Refer to pages 72, 73, Electronic Thermal Protection.)
For protection measures, use of a motor with an imbedded-type thermal relay in the motor coil is
recommended when running a motor at low speeds.
Restrictions on the installation of power-factor improvement capacitors (both input/output)
Do not install power-factor improvement capacitors on the input or output sides of the inverter. Large
currents containing high frequency elements may flow to the capacitors and adversely affect them.
Capacitors on the output side may cause the inverter to overcurrent trip. Install an input reactor or De­
link reactor (optional) for power-factor improvement.
Countermeasures against radio wave interference
The inverter may cause radio wave interference to audio equipment, etc., used near the inverter. In this
case, install a radio noise reduction filter (optional) on the inverter’s power source side, or shield the
cables to the motor with a conduit to reduce the interference. Contact your dealer for further details.
Cautions concerning ground faults
Verify that there are no incorrect connections between the motor and inverter and that there are no
short circuits in the motor before beginning operation. Do not ground the neutral point of a star-
connected motor.
Installation of an input reactor
An input reactor can be used to improve the input power-factor, to suppress high harmonic elements,
and to miminize the risk of damage to the inverter that may be caused by sudden power fluctuations.
Always install an input reactor when connecting the inverter to the following types of systems.
(1) When power source capacity is SOOkVA or more, and when power source capacity is greater than
the inverter capacity by a factor of 10 times or more.
When connecting the inverter to the same power system as thyristor-commutated control
equipment.
When connecting the inverter to the same power system as a distorted-wave generation source,
such as an arc furnace or thyristor-switched converter unit.
(
2
)
( 3 )
Leakage currents
Leakage currents may increase slightly depending on the connection method.
(1) When multiple inverters are connected to one ELCB, increase the ELCB current sensitivity value.
(2) Keep the wiring length between the inverter and motor as short as possible.
(3) Use an ELCB with high-harmonic suppression.
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