On 06/06/2019 10:25, alan_m wrote:
On 05/06/2019 21:57, Harry Bloomfield wrote:


It is designed to work with 120/240v and has heat destroyed it, my
idea is to fit a replacement but halve the 240v here, to average 120v,
using a 1N4007 diode. It will no doubt open up little slower, but no
problem.

Will it not get to the same temperature but just take longer?* Putting
2.5W or 5W into a device that cannot dissipate that power to heatsink or
air flow will cause the temperature to rise above that required to push
out the plunger to its maximum travel.

With that sort of actuator, even once it has opened, the power stays on,
adding heat energy. It will also be losing heat to the environment. The
temperature will stabilise when energy inflow equals energy outflow.

If you halve the inflow, you halve the outflow at equilibrium and as the
rate of energy loss is proportional to temperature difference (body to
air), that dictates that equilibrium will be established at a lower
actuator body temperature - so it *WILL* run cooler.

If the shutters take longer to open will the actuator be in a static or
a lower airflow for longer?

The actuator will still be fully extended by the time it reaches its
normal fully open temperature. It will continue to rise to its
equilibrium temperature, but the vent is already fully open by then.

SteveW