SAW Engine Performance & Tuning 2

Question 1

In a SAW power source with an engine-driven generator, what does a drooping volt-ampere characteristic primarily protect against?

Accepted Answer

Electrode stubbing and arc instability under varying load

Answer

A drooping (constant-current) characteristic limits current surges when the arc length shortens, preventing electrode stubbing and maintaining arc stability.

Question 2

When tuning a diesel engine driving a SAW generator for cold-weather starts, which adjustment is most important?

Accepted Answer

Verifying glow plug function and fuel viscosity rating

Answer

Cold diesel starts rely on adequate glow plug heat and low-viscosity fuel to ensure proper atomization and ignition at low temperatures.

Question 3

A SAW tractor's engine-driven wire feeder loses consistent wire feed speed as engine RPM fluctuates. The most likely cause is:

Accepted Answer

An unstable governor on the engine

Answer

Wire feed speed in engine-driven SAW systems is often tied to engine RPM; governor instability causes RPM swings that directly translate to inconsistent wire feed.

Question 4

During SAW, the open-circuit voltage (OCV) of an engine-driven power source is measured at 75V. What does this indicate about engine performance?

Accepted Answer

The engine is running at or near rated RPM producing full excitation

Answer

OCV at or above specified levels confirms the engine is spinning the generator at rated speed, ensuring full magnetic excitation and voltage output.

Question 5

An engine-driven SAW unit shows excessive black smoke under welding load. The most appropriate corrective action is:

Accepted Answer

Service the fuel injection system and air filter

Answer

Black smoke indicates rich combustion caused by insufficient air or poor fuel atomization; servicing the air filter and injectors restores proper air-fuel ratio.

(SAW) Submerged Arc Welding Certification Practice Test

(SAW) Submerged Arc Welding Certification Practice Test

SAW Engine Performance & Tuning 2