Toshiba Tosvert VF-A5 - Manual (Page 79)

u r . r
(Protection Parameters)
0 1 n
L- I i
Electronic thermal protection @
D L O OL selection
S t L /
S t C 1 Stall protection
The OL selection parameter| QL H can be set as follows,
0 L n setting value Function
0 Standard
+ 1 Soft-stall ON
+ 3 Motor overload ( Q L f i t ) trip OFF
Note) When 3 i s selected, both the + J and + ^functions are enabled.
* The motor overload trip can be enabled/disabled with OL i l , but the inverter overload trip is always
enabled.
Soft-stall function:
When the inverter detects an overload, the output frequency will automatically be lowered before the motor
overload trips { O L f i t )• The load current will stabilize at the reduced frequency, and operation will
continue without tripping.
This function is applicable to variable torque loads such as fans, pumps and blowers, which exhibit the
characteristic that when the operating speed decreases, the load current also decreases.
■ k Do not use soft-stall on constant torque loads (loads with a constant load current regardless of speed).
Inverter overload protection curve
t Time
: This protection curve cannot be changed or turned off
with parameter settings. This is built-in to protect the
inverter unit. If the inverter overload trip ( O L / n )
C r . P r activates, lower | 5h L f 1 in Cr.Pr (stall
protection level (current limit level adjustment)), and
increase the acceleration time ( I PCC I I or
R C E 3 ) ^0 decrease the chances of this occuring.
100%: Inverter rated current
llflJi 150% Output current
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