Omron VARISPEED E7 User Manual page 191

Setting Motor Protection Operation Time (L1-02)
Set the motor protection operation time in 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.
The following diagram shows an example of the characteristics of the electronic thermal protection operation
time (L1-02 = 1.0 min., operation at 50 Hz, general-purpose motor characteristics, when L1-01 is set to 1)
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 can-
not be protected even if this parameter has been set to 1 (enabled), because the internally calculated ther-
mal 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.
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 the Motor Overload Pre-Alarm
To enable the Motor overload pre-alarm enable the motor overload protection function (i.e., L1-01 must be set
to 1) and set H2-01 or H2-02 (multi-function output terminals M1-M2 and M3-M4 function selection) to 1F
(motor overload OL1 pre-alarm). If the electronic thermal value reaches minimum 90% of the overload detec-
tion level, the output terminal that has been set will be turned ON.
Application Precautions
With applications where the power supply is often turned ON and OFF, there is a risk that the motor cannot be
protected even if this parameter has been set to 1 to 3, because the thermal value will be reset.
6-34
Operating time (min.)
Fig 6.29 Motor Protection Operation Time
Cold start
Hot start
Motor current (%)
(E2-01 is set to 100%)
1/4
(fre-