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Unattended Start Protection
If the Run command is already set when power is turned ON, the inverter starts running
immediately after powerup. The Unattended Start Protection (USP) function prevents that
automatic startup, so that the inverter will not run without outside intervention. When USP
is active and you need to reset an alarm and resume running, either turn the Run
command OFF, or perform a reset operation by the terminal [RS] input or the keypad
Stop/reset key.
In the figure below, the [USP] feature is enabled. When the inverter power turns ON, the
motor does not start, even though the Run command is already active. Instead, it enters
the USP trip state, and displays
the alarm by turning OFF the Run command per this example (or applying a reset). Then
the Run command can turn ON again and start the inverter output.
Run command [FW,RV]
[USP] terminal 1
Alarm output terminal
Inverter output frequency
Inverter power supply 1
Option
Terminal
Code
Symbol
USP
Valid for inputs:
Required settings
Notes:
Note that when a USP error occurs and it is
canceled by a reset from a [RS] terminal input, the
inverter restarts running immediately.
Even when the trip state is canceled by turning
the terminal [RS] ON and OFF after an under
voltage protection
will be performed.
When the running command is active immediately
after the power is turned ON, a USP error will
occur. When this function is used, wait for at least
three (3) seconds after the powerup to generate a
Run command.
1
0
0
1
0
0
0
Events:
Function Name
Unattended Start
Protection
~
(none)
occurs, the USP function
error code. This requires outside intervention to reset
Alarm
cleared
command
State
ON
On powerup, the inverter will not resume a Run
command (mostly used in the US)
OFF
On powerup, the inverter will resume a Run
command that was active before power loss
Example (requires input configuration see
7
6
See I/O specs on
36
Run
Description
USP
5
4
3
2
1
L
page 23, 24.
t
page
66):
P24
PLC
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