In the choice of the ideal automation there are some aspects and suggestions to be considered. This article is aimed at exploring one of the most important and significant technical data appearing in our technical documentation: the duty cycle. This data should always be taken into consideration when choosing the type of motor to be used, but it is crucial to take a moment to fully understand what this means and how to interpret it correctly. The duty cycle is the ratio between ON time and OFF time, expressed as a %, which, if complied with, enables the actuator to be used without the thermal protection cutting in.
For example, to calculate the possible operating cycle on a 6-meter long sliding gate, with a manoeuvre speed of 10 m/minute (omitting slow-downs), a gate open time = 30 seconds and a duty cycle of 30%, we can calculate:
ton = opening time + closing time = The time during which the gate is moving
opening time = closing time = (6 m)/(10 m⁄min) = 6 m / 10m/minute = 0.6 minutes = 36 seconds
We can calculate the toff , which is the pause time, i.e. the time when the gate remains closed:
toff = Gate open time + Pause time between one cycle and the next
Given that the duty cycle is 30%, this means that:
t_ON/t_OFF = ton / toff = 30% = 0.3 therefore: toff= t_ON/0.3 = ton / 0.3 = ((36+36))/0.3 = 36 + 36 / 0.3 = 240 seconds
Thus the pause time between one cycle and the next = toff – gate open time = 240 – 30 = 210 seconds = 3.5 minutes
Therefore the operating cycle that can be set without the intervention of the thermal protection, is:
Opening = 36 seconds, Gate open time = 30 seconds, Closure = 36 seconds, Pause = 210 seconds
Atmospheric conditions and temperature can influence the data relating to the duty cycle, as well as the slow-downs. In fact, slow-downs increase the ON time for the same stroke length, but generally heat the actuator less than with movement at full speed. In general, the movement speed affects the heating curve of the motors and electronic components: the greater the speed the greater the heating, but the shorter the manoeuvre time for the same stroke length.
