Question 1
Three heater elements rated 60 ohms, 30 ohms, and 20 ohms are connected in parallel across a 120 V supply. What is the total current drawn from the supply?
Show answer & explanation
Correct answer: D - 12 A
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The USPS 955 exam has 128 questions and runs 1 hour 40 minutes.
These 10 free USPS 955 questions are organized by exam domain, so you can see how each part of the USPS Maintenance Exam 955 blueprint is tested. Reveal the answer and explanation under each question.
Three heater elements rated 60 ohms, 30 ohms, and 20 ohms are connected in parallel across a 120 V supply. What is the total current drawn from the supply?
Correct answer: D - 12 A
A single-phase transformer has 480 turns on the primary and 120 turns on the secondary. The primary is connected to 480 V and the secondary supplies a load drawing 20 A. Neglecting losses, what is the primary current?
Correct answer: B - 5 A
A technician is preparing to test the insulation resistance of a three-phase motor winding with a megohmmeter. Before applying the test voltage, the technician must FIRST:
Correct answer: A - Disconnect the motor leads and verify the circuit is de-energized
A three-phase induction motor operating on a 60 Hz supply has a nameplate full-load speed of 1,150 RPM. How many poles does the motor have?
Correct answer: C - 6 poles
A three-wire motor control circuit uses momentary START and STOP pushbuttons with a magnetic starter. The motor runs only while the START button is held and stops the instant it is released. The MOST likely cause is:
Correct answer: C - The holding (seal-in) auxiliary contact is not making
A motor turning at 1,750 RPM drives a 3 inch sheave, which is belted to a 10.5 inch sheave on a blower shaft. What is the approximate speed of the blower shaft?
Correct answer: A - 500 RPM
On a bench grinder, what is the maximum allowable distance between the work rest and the face of the abrasive wheel?
Correct answer: B - 1/8 inch
A double-acting hydraulic cylinder has a 4 inch bore and a 2 inch diameter rod, and the system operates at 1,500 psi. What is the approximate force available on the RETRACT stroke?
Correct answer: B - 14,137 lb
A centrifugal pump that has run normally for months begins making a sound like gravel passing through the casing, and discharge pressure fluctuates. The impeller vanes are later found to be pitted along their leading edges. The MOST likely cause is:
Correct answer: A - A clogged suction strainer or a partially closed suction valve
A 4,000 lb load is lifted with a two-leg bridle sling. Each leg forms an angle of 30 degrees with the horizontal. What is the approximate tension in EACH sling leg?
Correct answer: C - 4,000 lb
The USPS 955 exam also covers these domains. Drill them in the full free practice test:
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