Refer to the drawing of a valve motor control circuit (see figure below).
Note: Limit switch (LS) contacts are shown open regardless of valve position, but relay contacts are shown open/closed according to the standard convention for control circuit drawings.
Which one of the following describes the purpose of the alarm?
A. Alert the operator when the valve motor circuit has been energized for 10 seconds after pushbutton PB2 is depressed.
B. Alert the operator when the valve has not moved off its closed seat within 10 seconds of depressing pushbutton PB2.
C. Alert the operator that the valve is opening by sounding the alarm for 10 seconds after PB2 is depressed.
D. Alert the operator if the valve has not reached full open within 10 seconds of depressing pushbutton PB2.
Show Answer
Answer: B
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