5-26
Restart after momentary power failure (Frequency fall rate) (H14)
During restart after a momentary power failure, if the inverter output frequency and the idling
motor speed cannot be harmonized with each other, an overcurrent will flow, activating the
overcurrent limiter. If it happens, the inverter reduces the output frequency to match the idling
motor speed according to the reduction rate (Frequency fall rate: Hz/s) specified by H14.
Data for H14
Inverter’s action for the output frequency fall
0.00
Follow the deceleration time specified by F08
0.01 to 100.00 (Hz/s)
Follow data specified by H14
999
Follow the setting of the PI controller in the current limiter (of the
current limit control block shown in FRENIC-Multi User's Manual
(MEH457), Chapter 4, Section 4.4, Figure 4.3.1 ").
(The PI constant is prefixed inside the inverter.)
If
t
he frequency fall rate is too high, regeneration may take place at the moment the
motor rotation matches the inverter output frequency, causing an overvoltage trip.
On the contrary, if the frequency fall rate is too low, the time required for the output
, triggering the inverter overload prevention control.
F15
H63
frequency to match the motor speed (duration of current limiting action) may be
prolonged
, F16
Frequency Limiter (High and Low)
Low Limiter (Mode selection)
F15 and F16 specify the upper and lower limits of the output frequency, respectively.
H63 specifies the operation to be carried out when the reference frequency drops below the
low level specified by F16, as follows:
• If H63 = 0, the output frequency will be held at the low level specified by F16.
• If H63 = 1, the inverter decelerates to stop the motor.
reference frequency, be sure to change the maximum frequen
accordingly.
• When you change the frequency limiter (High) (F15) in order to raise the
cy (F03/A01)
• Maintain the following relationship among the data for frequency control:
F15 > F16, F15 > F23/A12, and F15 > F25
F03/A01 > F16
where, F23/A12 is of the starting frequency and F25 is of the stop frequency.
If you specify any wrong data for these function codes, the inverter may not run
the motor at the desired speed, or cannot start it normally.