Function Application
‑665‑
145% point and 4 minutes (T2) at the 155% point, the overload time at 150% of the
rated motor current is 5 minutes under the default settings. The overload time is
calculated using the following formula:
T = T1 + (T2 ‑ T1) x (I ‑ I1)/(I2 ‑ I1) = 4 + (6 ‑ 4) x (150% ‑ 145%)/(155% ‑ 145%) = 5
minutes
Therefore, to have an overload alarm reported when the motor runs at 150% of
rated motor current for 2 minutes, set the motor overload protection gain (F9‑01)
to 0.4 (2/5 = 0.4).
Set F9–01 properly based on the actual overload capacity of the motor. Note that setting
F9–01 to an excessively high value may easily result in motor damage caused by overtem‑
perature without warning.
Motor overload pre‑warning coefficient: When the motor overload detection level
reaches the value of this parameter, the corresponding multi‑functional output
terminal (DO) or fault relay outputs a motor overload pre‑warning signal. The value
of this parameter is a percentage of the time during which the motor runs
continuously at an overload point without triggering an overload alarm.
On the condition that F9‑01 (motor overload protection gain) is set to 1.00 and F9‑
02 (motor overload pre‑warning coefficient) is set to 80%, when the motor running
current reaches 145% of the rated motor current and the motor runs at this level
for 4.8 minutes (80% x 6), the multi‑functional DO terminal or fault relay outputs a
motor overload pre‑warning signal.
The motor overload pre‑warning function enables the control system to receive a
pre‑warning signal from a DO terminal before motor overload protection is
triggered. The pre‑warning coefficient determines how long in advance the AC drive
triggers a pre‑warning ahead of motor overload protection. A larger coefficient
means later transmission of the pre‑warning signal. When the accumulative output
current of the AC drive exceeds the product of overload time (value Y on the inverse
time lag curve of motor overload protection) multiplied by the motor overload pre‑
warning coefficient (F9‑02), the multi‑functional DO terminal of the AC drive
outputs a motor overload pre‑warning signal. When F9‑02 is set to 100%, the motor
overload pre‑warning signal is transmitted the same time when overload
protection is triggered.
To Next Page
Loading...
