Fuji Electric FRENIC-ECO, Instruction Manual

Page: 177 / 246

5-69
H12
Instantaneous Overcurrent Limiting
H12 specifies whether the inverter invokes the current limit processing or enters the overcurrent
trip when its output current exceeds the instantaneous overcurrent limiting level. Under the
current limit processing, the inverter immediately turns off its output gate to suppress the further
current increase and continues to control the output frequency.
Data for H12 Function
0
Disable
An overcurrent trip occurs at the instantaneous overcurrent limiting level.
1
Enable
The current limiting operation is effective.
If any problem occurs when the motor torque temporarily drops during current limiting processing,
it is necessary to cause an overcurrent trip (H12 = 0) and actuate a mechanical brake at the same
time.
Function codes F43 and F44 have current limit functions similar to that of function code
H12. Since the current limit functions of F43 and F44 implement the current control by
software, an operation delay occurs. When you have enabled the current limit by F43
and F44, enable the current limit operation by H12 as well, to obtain a quick response
current limiting.
Depending on the load, extremely short acceleration time may activate the current
limiting to suppress the increase of the inverter output frequency, causing the system
oscillation (hunting) or activating the inverter overvoltage trip (
0 u
alarm). When setting
the acceleration time, therefore, you need to take into account machinery
characteristics and moment of inertia of the load.
H30
y98
Communications Link Function (Mode selection)
Bus Link Function (Function selection)
H30 and y98 specify the sources of a frequency command and run command--"inverter itself" and
"computers or PLCs via the RS-485 communications link (standard or option) or field bus
(option)." H30 is for the RS-485 communications link, and y98 for the field bus.
Using the communications link function allows you to monitor the operation information of the
inverter and the function code data, set frequency commands, and issue run commands from a
remote location.
Command sources selectable
Command sources Description
Inverter itself
Sources except RS-485 communications link and field bus
Frequency command source: Specified by F01 and C30, or
multistep frequency command
Run command source: Via the keypad or digital input terminals
Via RS-485 communications link
(standard)
Via the standard RJ-45 port used for connecting keypad
Via RS-485 communications link
(option card)
Via RS-485 communications link (option card)
Via field bus (option)
Via field bus (option) using FA protocol such as DeviceNet or
PROFIBUS-DP
RS-485
RS-485