Mechanical End-Stops to Prevent the Automatic turner from Over-rotating
There has been a recent new random case in an older set where the turning movement has failed to stop, resulting in crushed eggs.
This was a clean machine with limit switches (older style) that still functioned normally after the event.
The focus fell onto the cross-line capacitors on the turning motor.
I have since spent countless hours of testing components here, and so have the manufacturers of the components involved.
However the tests are not conclusive. There are several factors that may cause a random over-turning.
Fitting mechanical stops as shown is positive inexpensive insurance.
It is also recommended that your incubator is plugged into a Surge Protector such as the ones used for all other electronic equipment.
Please email or call if you have any questions
..ooOOoo..INSTRUCTIONS – FIT MECHANICAL STOPS
Mechanical Stops will prevent the rack from over-rotating in the event the turning motor or a limit switch has a malfunction.
They are placed at the top of the turns as shown.
Here they are fitted 12” apart and on the opposite side wall from the turning mechanism.
The bolts are 3/8” x 4” Zinc Plated Coach Bolts. Under the cup, a section of the shank is square
Drill 3/8” holes inside but 13/32” holes outside. The square shank buries, and the head pulls down flush.
Bolts need to have less than 2” of bare shank - with no thread
1 Initiate a manual turn until the limit switch is clicked and the movement stops
2 Locate and mark the position of the first bolt along the side wall
3 Initiate a manual turn in the opposite direction and mark the second bolt
4 Drill 1/8” pilot holes from the inside, through the inside colourbond only
5 With a 3/8” bit and the drill held level, drill from the inside until it starts into the outer plate.
6 With a 13/32” bit, drill the hole from the outside in the outer plate
7 Insert a bolt, fit nut and washer and tighten until the head is flush and the nut is firm
8 Slip some plastic tubing over the bolts to keep things tidy and clean
9 Do a test run. Initiate a manual turn in both directions and check for correct position
Some fine tuning is possible by bending the metal arms that hold the limit switches.
10 Make sure your turns are timed and the turn duration is limited by adjusting F2
Take the rack to the backup start position - Up arrow to trip a switch, then back a short way
..ooOOoo..Run your Greatlander through a Surge Protector
For those who missed it in the reading ... it is prudent to run all electronic equipment through a Surge Protector.
In our case, the cross-line capacitor's rating is only 10% above the service voltage.
If that 10% buffer is exceeded for an instant, current `jumps' across the cross-line capacitor and the direction of the motor is reversed
This reverse rotation will now be fed via the capacitor NOT via the limit switch ... hence the absence of control and the over-rotation
A Surge Protector
will filter any external over-voltage spikes. It will also protect the controller.
If anyone is interested in the battery of tests that we have made please contact me