Amazon Maintenance Technician Sample Test

The correct answer is D.

A double-pole, double-throw (DPDT) relay, and its schematic is shown in the figure below. It contains six terminals labeled 1 through 6. The middle pin is the output port, and the side pins are connected to the circuits. The output is selected from the two circuits with the help of the manual switch on top of the relay. The simplest way to control two circuits is to use DPDT as shown in the figure below.

Therefore, D is the correct choice. Choice A cannot be correct because it can control only one circuit. Choice B provides two outputs rather than two inputs. In addition, if we use two DPST relays, it can provide the same result. However, it is mentioned to use a single relay. Therefore, C cannot be correct as well.

The correct answer is B.

A holding contact is also known as a latch. It stores the status of the tag mentioned on the holding contact. In the figure shown below, limit switch 2 is labeled, and holding contacts are encircled. There are four holding contacts tagged as LS2. Therefore, B is the correct choice.

The correct answer is A.

The difference between the three flames is rooted in the acetylene-oxygen ratio in the flame. A neutral flame has the exact ratio required for combustion. The neutral flame is solely a heating device, and does not react with the welded metal.

The carburizing flame has excess acetylene, which causes the welded metal to absorb carbon.

The oxidizing flame has excess oxygen, which causes the welded metal to oxidize. Due to its oxidizing effect, it is used mainly for non-ferrous metals such as bronze and copper.

The correct answer is C.

In the splash lubricating system, oil is mechanically splashed upwards from pans or trays in the crankcase, creating a mist that lubricates the internal parts of the mechanism. The splash method is an unreliable method since the oil level in the crankcase will have a substantial influence on the lubrication level. A high oil level may cause excess lubrication, whereas an oil level that is too low will cause inadequate lubrication. For that reason, splash method lubrication is only used in very small engines such as a lawnmower.

The correct answer is D.

The three components: Filter, Regulator and Lubricator (known also as the FRL unit) are designed to treat the air leaving the compressor before entering the system.

The filter strains the air of small particles and contaminations, the regulator supplies air at a determined, constant pressure, and the lubricator creates a mixture of air and oil mist to lubricate the system’s parts, thus improving their functioning and extending their service life.

The filter must be installed before the regulator, which, in turn, must be installed before the lubricator (so that the contaminating particles or lubricant oil particles do not interfere with the regulator’s action) . The filter is also installed before the lubricator so that the oil particles are not filtered from the air.

The correct answer is C.

To better understand the power factor concept, we will first explain the three types of power in an AC system: real power, reactive power and apparent power.
Real Power (or Active Power) is the power actually preforming work in the system (power consumed by the resistive component of the circuit). Measured in Watts [W].
Reactive Power is the power consumed by the system; it does no useful work and dissipates in the form of inducted magnetic fields or electrostatic fields. Measured in Volt-Amperes reactive [Var].
Apparent Power is the vector sum of the real power and reactive power (we do not expand on that matter since it is not required). Therefore it is always larger (in any practical AC system) or equal (in purely theoretical models) to the real power.

Power factor is defined as the ratio:

Since

Remember that the power factor may be negative if the direction of power flow is opposite to that initially defined.

The correct answer is D.

Tapping means creating threads in a hole. In CAD modeling, the holes can be tapped or not, depending on the assembly requirement. While making an engineering drawing of a part, the draftsman needs to specify whether the hole is tapped or not. If only the diameter is mentioned, that means there is no tapping required in the specific hole. The tapping is mentioned in an engineering drawing as “D-X”, where D is the diameter of the hole and X represents the tapping. The maximum diameter is D and the thread teeth diameter is “D-1/X”. This specification is for an inch system of engineering drawings. In the given drawing, there are four tapped holes. It is written as 1/4 -20, 1/4-28, 1/4-18, and 1/4-18. Therefore, D is the correct choice.

The correct answer is C.

Megohmmeters are ohmmeters (resistance measuring devices), which are able to measure very high resistances (in a scale of Megohms (millions of ohms). Therefore, they are used to test elements with very high electrical resistance – namely, insulation.

The correct answer is B.

When activated by AC current, the current changes direction as many as 60 times per second when alternating between positive and negative peaks. As such, there are 60 times per second when the current drops to zero, and as a result (since the solenoid's magnetic field is proportional to the current), so does the magnetic field inside the solenoid. That causes the return spring to overcome the solenoid's actuating force for a very brief moment, many times per second. This action results in a constant vibration of the armature causing a humming sound as well as extra stress on the solenoid's components.
This problem can be solved by a shading ring. The ring, a small conductive ring usually made of copper, generates a magnetic field in a 90 degrees phase difference to that created by the solenoid itself, thus keeping the armature in place when the current periodically drops to zero.