Filter
Top Products
E6581301
E-22
5
5.14 Setting the electronic thermal
VJT
VJTVJT
VJT
: Motor electronic thermal protection level 1
QNO
QNOQNO
QNO
: Electronic thermal protection characteristic selection
H
HH
H
: OL reduction starting frequency
H
HH
H
: Motor 150%-overload time limit
H
HH
H
: Temperature detection
[Parameter setting]
Title Function Adjustment range Default setting
VJT
Motor electronic
thermal
protection level 1
~ %
QNO
Electronic
thermal
protection
characteristic
selection
Default
setting
Motor type
Overload
protection
Overload stall
Standard
Motor
{
(protect) × (No stall)
{
(protect)
{
(stall)
× (No Protection) × (No stall)
× (No Protection)
{
(stall)
VF
Motor
(special
motor)
{
(protect) × (No stall)
{
(protect)
{
(stall)
× (No Protection) × (No stall)
× (No Protection)
{
(stall)
1) Setting the motor electronic thermal protection level 1 VJT
VJTVJT
VJT and electronic thermal protection
characteristics selection QNO
QNOQNO
QNO
The electronic thermal protection characteristics selection QNO is used to enable or disable the motor overload
trip function (QN) and the overload stall function.
The motor overload trip function (QN) needs to be selected with the parameter QNO, while the inverter overload
trip function (QN) is always activated.
[Using standard motors (other than motors intended for use with inverters)]
When a motor is used in the lower frequency range than the rated frequency, that will decrease the cooling effects
for the motor. This speeds up the start of overload detection operations when a standard motor is used in order to
prevent overheating.
■
■■
■ Setting of electronic thermal protection characteristics selection QNO
QNOQNO
QNO
Default setting Overload protection Overload stall
{
(protect) × (No stall)
{
(protect)
{
(stall)
× (No Protection) × (No stall)
× (No Protection)
{
(stall)
• Function
This parameter allows selection of the appropriate electronic thermal protection characteristics according to the
particular rating and characteristics of the motor.
Explanation of terms:
Overload stall (Soft stall)
The function of automatically lowering the output frequency before the motor overload trip function
QN is activated when the inverter detects that an excessive load is applied to the motor. (Lowers
maximum about 48Hz when basic frequency is 60Hz.) This function enables the inverter to output a
frequency commensurate with the load current so that the motor can keep running without tripping.
This function is useful for such loads as fans, pump, and blowers, which have the square reduction
torque characteristic that the current passed decreases as the rotating speed falls.
Note: Do not use this overload stall function for loads with a constant torque characteristic (e.g., a belt
conveyer to which a constant load current is always passed regardless of their speed).