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Energy Basics > Building Automation Systems > Flashcards

Building Automation Systems Flashcards

1
Q

__ __ control system utilizes an actuating device to control the process directly without asking for feedback

A

open loop

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2
Q

__ __ control system utilizes feedback to compare the measured variable to the desired result

A

Closed Loop

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3
Q

Refers to data received by the controller

A

input

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4
Q

refers to data received by the controller

A

output

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5
Q

a continuous signal that varies through a range of values. proportional

A

analog

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6
Q

a time-separated signal that carries information in binary form. only two state of positions; on or off. yes or no. open of closed.

A

digital

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7
Q

value of the controlled variable that is to be maintained

A

set point

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8
Q

actual measured value of the controlled variable

A

measured value

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9
Q

the difference between the set point and the actual value of the controlled variable

A

error

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10
Q

two position controller, it is the difference between the settting at which the controller operates at one position and the setting at which it changes to the other position.

A

differential

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11
Q

a type of controller for which the output can vary infinitely over the range of the controller

A

modulating controller

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12
Q

a controller for which an increase in the level of the sensor signal vs a controller for which an increase in the level of the sensor signal results in a decrease in the level of the controller output.

A

direct acting controller vs reverse acting controller

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13
Q

minimize pressure drop across valve

A

control valve sizing and pressure drop

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14
Q

excessive pressure drop could be

A 
poor selection (high Cv factor)
Valve and/or actuator impaired
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15
Q

the number of US gallons of water per minute at 60 degrees that will flow through a valve with a pressure drop of one psi

Flow (GPM) = Cv * square root of change in pressure (PSI)

A

flow coefficient

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16
Q

Proportional control is __ and the corrective action often __ the target

After arriving at the set point, there will be no controller action and you can get __ target.

proportional to size of error

A

reactive, overshoots, off

17
Q

Proportional, integral, and derivative are __ __ systems that use a feedback signal to control a certain actual

A

closed loop

18
Q

Integral Control increases corrective action in relation not only to the error but also to the….
Integral control corrective action if results aren’t achieved as time passes

A

time it has persisted

19
Q

Proportional + Integral control can __ the time to get to steady state

A

reduce

20
Q

With derivative control, if sudden changes occur, the response will be related to the __ __ __

derivative control is useful when trying to stay __ __ in a precisely controlled system

A

rate of change

on target

21
Q

__ control systems are operated by clean, dry, and oil free compressed air flow at low pressure.

includes: receiver controller, actuator and valve, damper actuator

safe and easy to operate, reliable in harsh environments
not very precise, sensitive to vibrations

A

pneumatic

22
Q

__ control is a process that transforms one or more input signals into different output signals so as to give the desired system response

instantaneous, very little affected by normal temps
very accurate
different manufactures used different signals so inoperable

A

Electrical

23
Q

__ __ controller received input from the sensor and then sens output signals in ‘packets’ using digital communication

Different _ _ _ can be networked together using a data bus

A

Direct Digital Control

24
Q

ASHRAE 135

A

BACnet - Building Automation and Control Networking protocol

25
Q

A __ typically runs HVAC systems
A __ automates the functions of a __ system and enables savings via lighting, metering, access control, and other systems
A __ system is a subset of the __
the __ will allow you to visualize and manage your building systems in such a way that you can create energy savings

A

control system
building automation system
control system

26
Q

What is an advantage of a hot water reset?

A

Maintain lowest hot water supply temp that will meet needs

reduces load on the boiler as well as thermal lasses throughout the distribution

27
Q

What is an advantage of a chilled water reset

A

Raises the temperature set point of water leaving the chiller

Most chilled water setting are designed with the heaviest anticipated cooling load

significant cost savings can result from resetting chilled water temps. in anticipation of cooling load

28
Q

Before a static pressure reset, all of the VAV boxes partially open creating static pressure in the main duct, typically around 2 inches. This results in ___ fan horsepower maintaining this __ than necessary set point.

After the static pressure reset, the DDC system monitors the VAV static pressure and lowest the pressure until only __ damper is completely ___, which is a better means of determining minimum flow requirements.

A

wasted, higher

one, open

29
Q

An economizer __ cooling energy by optimizing mixed air temperature
as the outside air allows, the outdoor air damper open __

A

reduces, more

30
Q

A room temperature sensor supplying information/feedback to an HVAC system is an example of: __ input, __ outpout

A

Analog Input, Closed Loop output

31
Q

An actuator mounted on a variable air volume box would be a decide that would receive an __ output signal

A

Output

32
Q

Which approach is most likely to provide the greatest improvement in boiler combustion efficiency (assuming no change in fuel)

  1. Increase stack temp and increase combustion air temp
  2. Fix all steam leaks
  3. Reduce stack temp and decrease combustion air temp
  4. Increase boiler excess oxygen and increase stack temp
  5. Reduce boiler excess air and reduce stack temp.
A
33
Q

Reducing excess air in boiler __ the oxygen in the stack and for better combustion efficiency

A

reduces

34
Q

Reducing the stack temperature by installing an economizer or combustion air pre-heater ___ the stack temperature rise and further improves efficiency

A

reduces

Energy Basics (15 decks)

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