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Optional Controlled Decel and Alarm at Power Loss
Operations
and Monitoring
4–4
Optional Controlled Decel and Alarm at Power Loss
With the default SJ300 inverter configuration, a sudden power loss will cause the inverter to
shut down immediately. If running at the time, the motor and load will coast to a stop. And
without power, the inverter’s alarm output will not activate. This default performance may be
fine for applications with loads such as fans and pumps. However, some loads may require
controlled decelerations upon power loss, or you may want an alarm signal upon power loss.
This section describes how to harness regenerative energy so that the motor/load actually
powers the inverter long enough to control a final deceleration and power the alarm output.
The diagram below shows the default configuration. Chapter 2 covered wiring the power source
to the inverter input and the inverter output to the motor. By default, the inverter’s internal
control circuit gets its power from two phases (R and T) from the input. The user-accessible
2-wire jumper (R–R0 and T–T0) connects input power to the control circuit.
To provide power to the control circuit after input power loss, you must change the control
circuit wiring as shown below (steps provided on following page).
U
V
W
Motor
R
S
T
T
R
R0
T0
Power source,
3-phase
2-wire
jumper
P
PD
RB
N
To optional
braking resistor /
braking unit
Control
circuit
Rectifier Inverter
Converter
DC bus
+
–
+
–
J51
Ferrite
filter
SJ300
AL0
AL2
AL1
To external
alarm circuit or
interface
L1
L2
L3
T1
T2
T3
U
V
W
Motor
R
S
T
T
R
R0
T0
Power source,
3-phase
2-wire
jumper,
20AWG
P
PD
RB
N
To optional
braking resistor /
braking unit
Control
circuit
Rectifier Inverter
Converter
DC bus
+
–
+
–
J51
Ferrite
filter
SJ300
AL0
AL2
AL1
To external
alarm circuit or
interface
L1
L2
L3