Hitachi NES1-004SB Quick Reference Manual page 127

Chapter 7 Explanation of Functions
*1 If the inverter trips because of overvoltage or overcurrent while decelerating the motor, the inverter will
display error code "E09" (undervoltage), and the motor will start free-running. If this error occurs,
prolong the deceleration time.
*2 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.
*3 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 undervoltage in the stopped
state(b004), the inverter will trip if the undervoltage failure continues over the allowable under-voltage
power failure time(b002). (See example 2.)
When restart mode(b001)=Trip (00) , the inverter will not trip if the undervoltage failure continues over
the allowable under-voltage power failure time(b002).
*4 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.
*5 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.
*6 when starting the motor with active 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" (b030=00):
Power supply
Inverter output
Motor frequency
(speed)
0
Free-running
t0
t2
t1
Free-running
Starting with
active
matching
t0 t2
frequency
(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
b007
Motor frequency
(speed)
0
7 - 52
Free-running
t0
t1
(b030=00) :
b007
Free-running
t2
t0
Starting with
0 Hz