Installation Considerations; Piping And Wiring; How Electrical Noise Occurs - O. Thompson Microflite Ultra 2000 Installation & Adjustment Manual

Section 4 Installation Considerations
The installer should minimize exposure to the following:
1. Dust, carbon, or metallic particles should not accumulate on any part of the control.
2. Vibration and shock.
3. Rapid temperature change, high humidities, high ambient temperatures.
4. Caustic fumes.
5. Electromagnetic interference. This may be caused by radio transmitters, high voltage inductive
spikes from unsuppressed relay coils, improper grounding, and improper wiring practices. The
following should be noted:
•
The outer door will protect against interference only if it is closed. When the door is open, do
not operate high wattage radios next to the microprocessor.
•
Noise from door operator reactors can cause a problem if mounted in the controller.
•
If the CRT shows lines, spikes or other signs of interference, check for electromagnetic
interference (noise) by checking the following:
Note: AC drives are very prone to cause noise interference. This is particularly evident on the
Diagnostic monitor while the car is running. This is a normal condition and will not
effect the operation of the controller.
1. Check for proper (water pipe) grounding.
2. Check that high voltage wiring is not running near the MPU board or monitor.
3. If the noise is seen when the door motor is operating (CX or OX are lit on the
screen), add suppression around the door operator circuitry.
4. Try to pinpoint when the noise occurs ( I.E. when the noise occurs, what relay
is picking or dropping.) Once the problem relay is pinpointed, add arc
suppression around the coil.
Note: Standard arc suppressors (resistor/capacitor networks) are used on AC relays, and
diode/resistor combinations work well for DC relays. Consult O. Thompson engineering
for proper component sizing.
4.1

Piping and Wiring

Proper routing of the signal and power wires for the car and dispatcher is essential to a trouble free
installation with any microprocessor based equipment. This part of the installation is where most people
turn their heads and say "oh, I didn't see that section." As much as it sounds like an "engineering
thing", low voltage and high voltage wiring cannot be run in the same conduit or duct.

4.1.1 How Electrical Noise Occurs

Electrical noise occurs in most cases when two wires run along side one another, one of them a high
power conductor, and the other of relatively low signal level conductor. As current flows through the
high power wire, magnetic lines of flux (voltage) expand outwards around the outside
of the wire. With a low signal level wire along side the high voltage wire, a voltage from the magnetic
lines of flux is induced in the low level conductor.
Revision: AA 2.1
Microflite Ultra 2000
Printed 03 - 15 - 03 3 - 1