Fuji Electric FRENIC-HVAC User Manual page 81

(6) When an output circuit filter is inserted in the secondary circuit or the wiring between the
inverter and the motor is long, a voltage loss occurs due to reactance of the filter or wiring so that
the insufficient voltage may cause output current oscillation or a lack of motor output torque. To
avoid it, select the constant torque load by setting the function code F37 (Load Selection/Auto
Torque Boost/Auto Energy Saving Operation 1) to "1" and keep the inverter output voltage at a
higher level by configuring H50/H52 (Non-linear V/f Pattern, Frequency) and H51/H53
(Non-linear V/f Pattern, Voltage).
 Precautions for connection of peripheral equipment
(1) Power supply lines (Using AC reactor)
If the interphase voltage unbalance ratio of the inverter power supply is 2 to 3%, use an optional
AC reactor (ACR).
Interphase voltage unbalance
(2) Molded case circuit breaker (MCCB) or residual-current-operated protective device (RCD)/earth
leakage circuit breaker (ELCB)
Install a recommended MCCB or RCD/ELCB (with overcurrent protection) in the primary
circuit of the inverter to protect the wiring. Since using an MCCB or RCD/ELCB with a lager
capacity than recommended ones breaks the protective coordination of the power supply system,
be sure to select recommended ones. Also select ones with short-circuit breaking capacity
suitable for the power source impedance.
If no zero-phase current (earth leakage current) detective device such as a ground-fault relay is installed
in the upstream power supply line in order to avoid the entire power supply system's shutdown
undesirable to factory operation, install a residual-current-operated protective device (RCD)/earth
leakage circuit breaker (ELCB) individually to inverters to break the individual inverter power supply
lines only.
Otherwise, a fire could occur.
(3) Magnetic contactor (MC) in the inverter input (primary) circuit
Avoid frequent ON/OFF operation of the magnetic contactor (MC) in the input circuit; otherwise,
the inverter failure may result. If frequent start/stop of the motor is required, use FWD/REV
terminal signals or the
The frequency of the MC's ON/OFF should not be more than once per 30 minutes. To assure
5-year or longer service life of the inverter, it should not be more than once per hour.
From the system's safety point of view, it is recommended to employ such a sequence that
shuts down the magnetic contactor (MC) in the inverter input circuit with an alarm output
signal ALM issued on inverter's programmable output terminals. The sequence minimizes
the secondary damage even if the inverter breaks.
When the sequence is employed, connecting the MC's primary power line to the inverter's
auxiliary control power input makes it possible to monitor the inverter's alarm status on the
keypad.
(4) Magnetic contactor (MC) in the inverter output (secondary) circuit
If a magnetic contactor (MC) is inserted in the inverter's output (secondary) circuit for switching
the motor to a commercial power or for any other purposes, it should be switched on and off
when both the inverter and motor are completely stopped. This prevents the contact point from
getting rough due to a switching arc of the MC. The MC should not be equipped with any main
circuit surge killer (Fuji SZ-ZM etc.).
Applying a commercial power to the inverter's output circuit breaks the inverter. To avoid it,
interlock the MC on the motor's commercial power line with the one in the inverter output circuit
so that they are not switched ON at the same time.
(5) Surge absorber/surge killer
Do not install any surge absorber or surge killer in the inverter's output (secondary) lines.
Max. voltage ( V)
( %) =
Three - phase average
/ and keys on the inverter's keypad.
2-48
Min. voltage ( V)
(See IEC/EN 61800-3.)
× 67
voltage ( V)