Toshiba VF-SX - Manual (Page 24)

TOSHIBA 5-5
5.3 Installation of a Primary Magnetic Contactor (MC)
1. Install a magnetic contactor (HC) on the line side of the inverter to prevent
restart after either a loss of power, a trip of an external overload relay, or
an operation of the internal drive protective device.
2. The VF-SX has an internal fault detection relay. The HC can be opened when
the inverter protective circuit operates by connecting this contact point to the
primary MC operation circuit.
3. The inverter can be used without an HC. In this case use a shunt trip style
main breaker (MCCB) and open the main circuit by tripping the breaker when the
inverter protective circuitry operates.
4. When using a braking resistor with an overload relay, install an HC or an
MCCB with shunt trip on the line side of the inverter. Connect these devices so
that the power circuit will open when the internal fault detection relay (Ft) or
externally installed overload relay operates. Emergency stop is also possible
by connecting the overload relay contact point between the terminals of SS3 (EX)
and CC of the inverter. See Chapter 11 for details of the Emergency Stop
parameter.
5. Use control signals on terminals F, R, and CC for frequent starting and
stopping. Avoid turning the inverter on and off with the primary HC.
6. Always install a surge suppressor across any contactor coil.
5.4 Installation of an Output Magnetic Contactor (MC)
1. Avoid starting and stopping the motor with an output contactor (HC) installed
between the inverter and the motor. Excessive surge currents could damage the
output devices of the drive. Use control signals on terminals F, R, and CC
instead.
2. For Bypass Operation; Be sure the motor has stopped and the drive is OFF
before turning on the bypass contactor to run the motor directly from line power.
Use an external timer, PLC, or similar device as required. Always make sure that
the bypass contactor does not allow voltage to backfeed into the inverter output
terminals.