17 terms

Chapter 109 • Electronic Controls for Heating Systems

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An advantage of an electronic control system is that
a) the controllers can accept a wide variety of inputs.
b) it is inexpensive to operate.
c) it is inexpensive to install.
d) it is very compact.
a
An electronic controller is used to position
a) a final control element.
b) an actuator.
c) an electronic instrument.
d) a transmitter
b
Types of metals used to manufacture the wires used in RTDs are
a) nickel.
b) iron.
c) platinum.
d) all of the above.
d
Electric to pneumatic transducers convert a modulating 2 to 10 V DC signal to a pneumati c signal of _____ to ______ kPa.
a) 0, 90
b) 3, 15
c) 12, 120
d) 0, 125
a
An electronic pressure sensor consists of a ______________ that converts pressure changes into different variables.
a) thermistor
b) transmitter
c) thermocouple
d) RTD
b
Authority or Compensation authority is the:

a) process of automatically adjusting the setpoint of a controller
b) point in which the compensation effect is reversed in action
c) system element that senses a variable other than the controlled variable
d) setting that indicates the effect a compensating sensor has on the main setpoint
e) entity that awards compensation after a workplace injury.
d
Setpoint deviation is also called:
a) derivative
b) proportional band
c) offset
d) integral
e) gain
c
Proportional band or throttling range is the:

a) control method in which the final control element moves proportionally to the deviation of the controlled variable from the setpoint
b) control algorithm that combines the proportional and integral algorithms
c) compensation action where a decrease in the compensation variable has the same effect as an increase in the controlled variable
d) control point range through which the controlled variable must pass to drive the final control element through its full range
e) sustained deviation between the control point and the setpoint of a proportional control system under stable operating conditions
d
A direct acting controller:
a) increases its output signal on an increased input signal b) increases its output signal on a decreased input signal c) only handles direct acting inputs
d) only handles reverse acting inputs
e) decreases its output signal on an increased input signal
a
An electronic control system is comprised of a
a) meter, sensor, and valve
b) sensor, controller, and final control element
c) sensor, transmitter, and thermostat
d) controller, thermostat, and sensor
e) thermostat, electronic controls, and furnace
b
An example of a final control element is a
a) thermostat
b) fire eye
c) relay
d) damper
e) thermocouple
d
The electrical resistance of a thermistor will
a) decrease when cooled
b) decrease when heated
c) increase when heated
d) remain constant with temperature changes
e) none of the above
b
Resistance temperature devices can provide a relatively linear resistance variation from
a) -60 to 80 degrees C
b) -40 to 120 degrees C
c) -40 to 250 degrees C
d) 0 to 100 degrees C
e) 40 to 100 degrees C
b
Transmitters or transducers can measure
a) temperature
b) air flow
c) air flow velocity
d) water flow
e) all of the above
e
A pressure sensor converts pressure changes into
a) an electrical signal
b) a change in electrical resistance
c) variables such as voltage, current, or resistance
d) air pressure
e) a temperature change
c
Electronic controllers can be divided into two types
a) on or off
b) modulating and direct acting
c) indirect and direct acting
d) on or off and modulating
e) actuators and relays
d
A transducer is a device that is used to
a) generate a set point
b) produce an off or on signal
c) convert direct acting to reverse acting
d) amplify an electronic signal, or convert it to another energy form
e) filter an electronic signal
d