What type of compressors are most commonly used in rooftop packaged units?
A) Hermetic rotary and hermetic centrifugal compressors
B) Semihermetic scroll or semihermetic rotary compressors
C) Open-type centrifugal and open-type screw compressors
D) Hermetic reciprocating or hermetic scroll compressors
D
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Speed regulation is accomplished by sensing the speed of the motor and ____.
a. connecting current transformers to the input of the drive b. feeding this information back to the drive c. sensing the increase in current as load is added d. adjusting this speed
In the inverting amplifier, which formula is used to calculate the amount of gain in the circuit?
A. R1 x R2 B. R2/R1 C. (R1 + R2)/R1 D. R2/(R1 + R2)
The term ____________________ indicates the source of heat while the system is operating in the heating mode and the medium that is ultimately being treated.
Fill in the blank(s) with the appropriate word(s).
These organs labeled M produce hormones involved in
A) digestion.
B) respiration.
C) reproduction.
D) muscle contraction.
E) calcium absorption from blood.