Omron VARISPEED F7 User Manual page 235

Setting Motor Overload Protection Characteristics (L1-01)
Set the overload protection function in L1-01 according to the used motor.
The induction motor's cooling abilities vary with the motor type. Consequently, you must select the electronic
thermal protection characteristics.
Set L1-01 to:
0: to disable the thermal motor protection function.
1: to enable the thermal motor protection for a fan cooled general purpose motor (self-cooled).
2: to enable the thermal motor protection for an inverter motor (externally cooled).
3: to enable the thermal motor protection for a special vector motor (externally cooled).
Setting Motor Protection Operation Time (L1-02)
The motor protection operation time is the time for that the motor can handle a 150% overload when it was
running with the rated load before (i.e. operating temperature was reached before applying the 150% over-
load). Set the motor protection operation time in L1-02. The factory setting is 60 sec.
Fig 6.55
1.0 min., operation at 60 Hz, general-purpose motor characteristics, when L1-01 is set to 1)
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Setting Precautions
If multiple motors are connected to one inverter, set parameter L1-01 to 0 (disabled). To protect each of the
•
motors, use a control circuit that switches off the inverter output when one of the motors overheats.
With applications where the power supply is often turned ON and OFF, there is a risk that the motor cannot
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be protected even if this parameter has been set to 1 (enabled), because the thermal value will be reset after
inverter power supply switch off.
For safe overload tripping, set the value in parameter L1-02 to a low setting.
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When using a general-purpose motor (standard motor), the cooling ability will be lowered by f
•
quency). Consequently, a low output frequency may cause motor overload protection (OL1) to occur, even
when the output current is below the rated current. If the motor is operated at the rated current at a low fre-
quency, use a special motor which is externally cooled.
Setting a Motor Overload Pre-Alarm
A motor overload pre-alarm output can be programmed to one of the multi-function digital output (H2-
=1F) when the motor overload protection function is enabled (i.e., L1-01 is set to a value different from 0.
If the electronic thermal value reaches minimum 90% of the overload detection level, the output terminal that
has been set will be turned and remain ON as long as the thermal value does not fall below those 90%.
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6-
shows an example of the characteristics of the electronic thermal protection operation time (L1-02 =
Operating time (min.)
Fig 6.55 Motor Protection Operation Time
Cold start
Hot start
Motor current (%)
E2-01 is set to 100%
1/4
(fre-