Explanation of Function
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Commercial power source switching(CS)
This function is used for systems with an excessive amount of starting
torque requirements. The motor would be started direct-on-line and then
when the motor had started the inverter would take over. This function is
comonly used to reduce the costing of the inverter. A system may require
55KW’s to start but only 15KW’s to run at constant speed, therefore, a 15KW rated inverter would be
sufficient when
using this function. Assign 14(CS) to an intelligent input terminal.
Using the example below. When the motor has been started direct-on-line, Mg2 is switched OFF and Mg3 is
switched on. With the Forward command to the inverter already on the CS terminal is switched on and Mg1
is
closed. The Inverter will then read the motor RPM and when the CS terminal is switched OFF the retry wait
time
(b003) is started.
Once the wait time has elapsed the inverter will then start and match the frequency which is set (b007).
When the Earth Leakage Breaker (ELB) trips on ground fault, the commercial circuit will not operate. When
a backup
is required, take the supply from the commercial circuit ELBC.
For FWY, RVY, CSY, use control relays. The sequence above is reference to the circuit and timing diagram
below.
If an over-current trip occurs when frequency matching, extend the retry wait time (b003).
Connection figure example and timing on commercial power source switching
b003 : retry waiting time
b007 : frequency setting to match
C001-C008 : Intelligent
Relation code
Mg2
Motor
R
S
T
U
V
W
O
L
FW
RV
CS
CM1
AL1
AL2
AL0
THRY
Mg1
Mg3
ELBC
NFB
FWY
RVY
CSY
H
To
Ro
Mg1
Mg2
Mg3
FW
ON
ON
ON
ON
Operation
20ms
over
Frequency
matching and
operation
b003
IPS
WAIT
Normally set for 0.5-1 seconds
Interlock time of Mg2 and Mg3
(0.5-1 second)
OFF
Inverter output
CS
