Sanken S06-4A005-B Instruction Manual page 104

Protection functions
The function blocks related to inverter protection function setting are described as follows.
F1701 Output current limiting function
The current at which the output current limiting function begins to work can be specified. This is useful for driving a motor with a
small capacity compared with that of the inverter, or to make the best use of the inverter capacity to achieve the speediest acceleration.
Code No. Function Name
F1701 Output current limiting
function
● The value is set with the ratio to rated current.
● The so-called output current limiting function is used to limit the inverter's output current to prevent overload during
acceleration/deceleration or during normal operation. Use of this function enables the inverter to temporarily operate in the ways
described below:
1) During acceleration/deceleration: Reduce the acceleration/deceleration slope. This extends the time until the set frequency is
reached. The extended time varies depending on the magnitude of this setting and the inertia of the load. Generally,
accelerating or deceleration of a load with a large inertia requires a considerable current, requiring a relatively high setting.
Example 1) When F1701=200% (Mode A).
Maximum use of the inverter capacity to minimize the acceleration/deceleration time.
(In mode B, the maximum value of F1701 is 150%)
Example 2) Set current limit to the same value as the rated current of a motor with small capacity:
F1701 = (rated motor current/rated inverter current) × 100[%].
However, the drive frequency can only be specified within a range of 50 - 200% of the rated current of the
inverter. (in mode A)
(Possible range of setting is 50-150% in mode B）
2) During constant speed operation: When the inverter's output current exceeds this setting, the output frequency is automatically
reduced. The output frequency is reduced with the acceleration/deceleration slope specified by F1703.
Note 1: The current limiting function during normal operation is generally useful for loads with a reduced torque such as
fans and pumps. However, this function has an adverse effect on overloads during constant speed operation with
loads with normal and constant torque. The factory preset, therefore, of F1703 (Output current limiting function at
constant speed)= 0 disables the output current limiting function during operation. When driving reduced torque
load, if the F1703 ≠ 0, it is recommend to effectively use the output current limiting function during constant speed
operation.
Note 2: During the acceleration/deceleration caused by the output current limiting function in constant speed operation, the
output current limiting function during acceleration/deceleration described in 1) and overvoltage stalling prevention
function do not work.
● In vector control mode (speed control mode), because the torque limiter function is used to limit current, this function may not
work.
Reference parameter
F1003 (V/f pattern selection).
F1320 (Specification selection).
F1703 (Output current limiting function at constant speed).
Electric thermal setting
F1702
The current at which the electric thermal begins to work (electric thermal overload setting) is specified as a ratio to the rated inverter
current. Rated current is the base of the ratio.
Code No. Function Name
F1702 Electric thermal setting
● When a motor with a small capacity is driven, F1702 should be set to a small value which matches the rated motor current.(Refer to
example 1)
● For general-purpose motors, due to low cooling efficiency of the motor in the low speed zone, the electric thermal works faster as
the frequency decreases. When using an inverter-driven motor, current can not be compensated according to the frequency value.
Refer to F1705 (motor types).
● The electric thermal overload function also works during DC braking.
Data Content
A MODEL
0：No function
50～200%
B MODEL
0：No function
50～150%
Data Content
0：No function
20～105%
- 103 -
Setting Resolution Factory Presets
1% 150
120
Setting Resolution Factory Presets
1% 100