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• Use a built-in discharge resistor in the following conditions:
Regeneration time per cycle:
Service rate:
less than 5 seconds
3% ED maximum
If you need to use your inverter under conditions exceeding those specified above, connect a
regenerative resistor having the necessary heat capacity.
• When the inverter is subjected to frequent run and stop operation, the temperature of the built-in
regenerative discharge resistor will rise to 150·C due to heat build up. Thus you should pay
adequate attention to the safety precautions for selecting an installation site. (Refer to Section
1.1 (page 2 )
• When you use a regenerative discharge resistor or a regenerative discharge unit, install a
magnetiC contactor (MC) or a molded case circuit breaker (MCCB) with trip coil on the inverter'
s power supply side. This will allow the power supply circuit to open when the inverter's built-in
fault detection relay (FL) and the externally mounted overload relay are activated.
3.18 Universal unit setting and display [
dS,o.2 ]
This function not only permits use of the inverter's monitor display for indicating a motor's revolution
speed,
line speed, and frequency, but to set them via the inverter's operating panel.
The VF-A3 inverter's universal unit multiplication factor
[dSP.2]
determines the multiplication
factor of a frequncy indication within a range of 0.01 to 200,as well as 0
(OFF).
Indication on the monitor display
= universal unit multiplication factor x frequency value
Indicated values on the monitor display range from 0.00 to 9999. When the value exceeds 9999, the
most significant 4 digits from the 5th place through the 2nd place to the left of the decimal point
will blink on and off on the display monitor.
[Example settings]
1)
Revolution speed setting and indication
For a 4-pole motor, if you set the universal unit multiplication factor
[dS,o.2J
at 30, the monitor
display will show revolutions within a range of from 0 to 1800 rpm at a run frequency of from
OHz to 60 Hz. The frequency via the inverter's operating panel must be set by revolutions (9
-1800rpm).
2)
Line speed setting and indication
If you set the universal unit multiplication factor
[dSP.2 ]
at 0.1, the monitor display will show
a linear speed of 5m/sec at 50Hz. The frequency via the inverter's operating panel must be
set by a line speed (5).
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