CFESA Test Equipment and Technical Documentation

Question 1

A technician is checking the combustion efficiency of a commercial gas range burner. Which instrument is used to measure flue gas oxygen (O₂) or carbon dioxide (CO₂) percentage for this analysis?

Accepted Answer

Combustion analyzer (flue gas analyzer)

Answer

A combustion analyzer samples flue gas and measures O₂, CO₂, CO, flue temperature, and calculates combustion efficiency. This data is essential for verifying proper air-to-fuel ratio. Other instruments listed measure electrical current, gas pressure, or temperature — not combustion gas composition.

Question 2

When using a manifold gauge set on a refrigeration system, what does an abnormally high suction (low-side) pressure combined with a high discharge (high-side) pressure typically indicate?

Accepted Answer

Overcharge of refrigerant or a non-condensable gas in the system

Answer

Both high suction and high discharge pressures together indicate the system is working against excessive condensing load — most commonly caused by refrigerant overcharge or air/non-condensable gases trapped in the system (which raise head pressure without useful refrigeration effect). Low charge produces low suction AND low discharge pressure; restriction produces low suction and normal/high discharge; a weak compressor produces high suction and low discharge.

Question 3

A technician uses a clamp-on ammeter and reads 18A on a 208V single-phase motor nameplate-rated at 15A FLA. What is the correct interpretation?

Accepted Answer

The motor is drawing 20% above its Full Load Amperage, indicating a possible overload condition that should be investigated

Answer

FLA is the maximum continuous current rating for safe motor operation. Running at 120% FLA (18A vs 15A) elevates winding temperature, accelerating insulation breakdown. NEMA allows a 115–125% service factor depending on the motor, but this should be investigated — common causes include mechanical overload, low voltage, or a failing motor.

Question 4

On a ladder-style wiring diagram, what does a normally open (N.O.) contact symbol indicate about the contact's state when the controlling coil is DE-energized?

Accepted Answer

The contact is open (no current flow) when the coil is de-energized

Answer

By definition, a Normally Open contact is open (circuit interrupted) in its normal, unactuated state — i.e., when the controlling relay or contactor coil is de-energized. It closes (allows current) only when the coil is energized. This is fundamental to reading ladder diagrams correctly.

Question 5

A technician needs to verify whether a heating element's insulation has broken down to the equipment chassis (ground fault). Which instrument is most appropriate?

Accepted Answer

Megohmmeter (insulation resistance tester)

Answer

A standard DMM measures resistance up to a few megohms with low test voltage (~9V), insufficient to stress the insulation as line voltage does. A megohmmeter applies 500–1000V DC and measures insulation resistance in the hundreds of megohms, revealing degraded insulation that would pass a DMM continuity check but fail in service. This is the correct tool for insulation integrity testing.

CFESA - Commercial Food Equipment Service Association Practice Test

CFESA - Commercial Food Equipment Service Association Practice Test

CFESA Test Equipment and Technical Documentation