Page 100 - Apprentice Manual_Neat

S5-Q131.) Gain is critical to an Electronic Speed Control system. If gain is set too low, what will likely result?

a.) Speed will fluctuate wildly under no-load conditions
This would likely be from the gain set to high.
b.) *Frequency will drop too low for too long when load is applied
Correct. I the gain is too low, the speed will drop when load is brought online. If speed drops,
frequency drops also.
c.) The unit will likely go into over-speed at start-up and immediately shut down
This would likely be from a failed speed or over-speed sensor.
d.) The unit will respond to load too quickly and go into an over-voltage shut-down
This would likely be from the gain set too high, but would have no affect on voltage output.

S5-Q132.) Magnetic Pick-ups have what type of output?

a.) Resistance
Magnetism has nothing to do with resistance.
b.) *VAC
Correct. The motion of a ferrous metal past the magnetic pick-up causes an alternating current
to be created.
c.) Inductance
While it is magnetic, it has nothing to do with inductance.
d.) 4 – 20 Milliamps
The output is in the micro amp range.

S5-Q133.) Why is shielded wire required to carry the signal of a Magnetic Pick-up?

a.) To protect the wire from engine heat
Engine heat should not be a factor. This should be a property of the insulation.
b.) To protect the wire from chafing
While it may well perform this function due to poor installation, this is not the primary function of
shielding.
c.) *To protect the signal from external noise
Correct. Shielding collects unwanted noise and shunts it to ground before it can become a
problem to the primary signal. Shielding should always be terminated to ground, but at one
end only to prevent ground loops.
d.) Unshielded wire is preferred due to the tight confines of the location of the pick-up.
This is not true. The engine is a very noisy area with spark plugs, computers and other electronics.

S5-Q134.) What is the most common failure found in mechanical governors?

a.) *Bearings
Correct. Bearings are the weakest link in a mechanical governor. They are the primary moving
part and may not receive proper lubrication.
b.) Magnetic pick-up
A very reliable device. It has no moving parts.
c.) Broken wires to the actuator
The actuator is mechanically linked.
d.) Leaky air couplings
There is no air on a mechanical system.

EGSA Apprentice Certification Program Study Guide - Page 92