Hitachi L700 SERIES Instruction Manual page 96

Chapter 4 Explanation of Functions
*1 If the inverter trips because of overvoltage or overcurrent while decelerating the motor, the inverter will
display error code "E16" (instantaneous power failure), and the motor will start free-running. If this
error occurs, prolong the deceleration time.
*2 If a DC voltage (P-N) is supplied to control power supply terminals R0 and T0, the inverter may detect
undervoltage and trip when the inverter power is turned off. If this cause a problem in your system,
specify "00" or "02" for the trip selection.
*3 The inverter may start the motor with 0 Hz if:
1) the output frequency is not more than half the base frequency or
2) the voltage induced on the motor is attenuated quickly.
*4 Even when a retry operation (01 to 03)is specified for the selection of restart mode (b001) and
"disabling tripping" (00 or 02) is specified for the selection of a trip after instantaneous power failure or
undervoltage in the stopped state, the inverter will trip if the instantaneous power failure continues over
the allowable under-voltage power failure time. (See example 2.)
*5 Even when a retry operation is specified for the trip selection, the inverter will trip if the cause of trip is
not removed by the end of the retry wait time before motor restart (b003). If this occurs, prolong the
retry wait time.
*6 Even when a retry operation is specified for the retry selection, the inverter will trip if the undervoltage
status continues for 40 seconds or more.
*7 when starting the motor with matching frequency is selected, inverter may restart suddenly by alarm
resetting, resetting and retry-start.
The figures below show the timing charts for starting with a matching frequency (when "02" is specified for
the selection of restart mode [b001]).
t0: Duration of instantaneous power failure
t1: Allowable under-voltage power failure time (b002)
t2: Retry wait time before motor restart (b003)
(Example 1)
Power supply
Inverter output
Motor speed
(Example 3) When the motor frequency (speed)
is more than the setting of "b007":
Power supply
Inverter output
Motor frequency
(speed)
0
Free-running
t0 t2
t1
Free-running
Starting with
matching
frequency
t0 t2
(Example 2)
Power supply
Inverter output
Motor speed
(Example 4) When the motor frequency (speed)
is less than the setting of "b007":
Power supply
Inverter output
Motor frequency
b007
(speed)
0
4 - 34
Free-running
t0
t1
Free-running
b007
t2
t0 Starting with
0 Hz