It is strongly advisable that the brake-on delay be set longer than the ramp time in order to
avoid damaging of the brake.
0-2
3
4
No brake-off control
Brake-off ctrl, 2 limits
Brake-on/off crtl, 1 limit
0-2
3
4
No brake-off control
Brake-off ctrl,
torque limit
0-2
3-4
AND
OFF-
DELAY
COUNT
ON-
DELAY
COUNT
ID346
ID348
ID315
ID346
0-2
3
0-2
3
0-3
4
ID316
ID347
0-3
4
≤
3
4
Run state
No Run request
AND
OR
TRUE
f
out
≥ ID347
TRUE
Motor torque ≥ ID349
Brake-on ctrl, 2 limits
No brake-on control
Brake-on/off crtl, 1 limit
No brake-on control
OR
f
out
Fault
NOT
Reversing
No run request
OR
Brake-off control
Brake-on
control
Brake off
Brake on
Fig. 93: Brake control logic
When using the Master Follower function, the follower drive will open the brake at the same
time with the Master even if the Follower's conditions for brake opening have not been met.
8.4
PARAMETERS OF MOTOR THERMAL PROTECTION (IDS 704 TO 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
energised, the calculations are reset.
PARAMETER DESCRIPTIONS
VACON · 369
24-HOUR S358 (0)201 212 575 · EMAIL: [email protected]
8
