Parameters Of Motor Thermal Protection (Ids 704-708) - Danfoss VACON NX All-in-One Application Manual

VACON® NX All-in-One
Application Guide
No brake-off control
ID346
Brake-off ctrl, 2 limits
Brake-on/off crtl, 1 limit
No brake-off control
ID348
Brake-off ctrl,
torque limit
Motor torque ≥ ID349
Run state
No Run request
Reversing
No run request
No brake-on control
ID315
Brake-on ctrl, 2 limits
No brake-on control
ID346
Brake-on/off crtl, 1 limit
Fault
Illustration 98: Brake Control Logic
When using the Master Follower function, the follower drive opens the brake at the same time with the Master even if the Follower's
conditions for brake opening have not been met.
10.621 Parameters of Motor Thermal Protection (IDs 704–708)
The motor thermal protection prevents the motor from becoming too hot.
The AC drive can supply a current that is higher than the nominal current. The high current can be necessary to the load, and it must
be used. In these conditions, there is a risk of a thermal overload. Low frequencies have a higher risk. At low frequencies, the cooling
effect and the capacity of the motor decrease. If the motor has an external fan, the load reduction at low frequencies is small.
The motor thermal protection is based on calculations. The protection function uses the output current of the drive to know what is
the load on the motor. If the control board is not energized, the calculations are reset.
The motor thermal protection can be adjusted with parameters. The thermal current IT specifies the load current above which the
motor is overloaded. This current limit is a function of the output frequency.
The thermal stage of the motor can be monitored on the control panel display. See the User Manual of the product.
When using long motor cables (maximum 100 m) with small drives (≤1.5 kW), the motor current that the drive measures can be
much higher than the actual motor current. It is because there are capacitive currents in the motor cable.
MOTOR DAMAGE HAZARD
If the airflow is blocked, the function does not protect the motor, and the motor can become too hot.
-
Make sure that the airflow to the motor is not blocked.
308 | Danfoss A/S © 2023.02
0-2
3
4
0-2
TRUE
f ≥ ID347
3-4
out
0-2
3
4
0-2
TRUE
3
ON-
DELAY
COUNT
OR
0-2
3
3
OR
0-3
4
4
0-3
ID316
ID347 4
f
out
C A U T I O N
OFF-
AND
DELAY
COUNT
NOT
AND
≤
Parameter Descriptions
Brake off
Brake on
OR
AB296635287482en-000301 / DPD00903