Controls Flashcards
What are the main functions of a BMS?
Monitor and control.
Name a device that is considered to use an “Analog Output” type point.
Damper motor, fan speed control
What does DDC stand for?
Direct Digital Control
Give an example of the use of a pressure differential switch.
Pump status, airflow status.
What is dead-band?
The range where there is no action needed surrounding a set point.
Describe a device that is considered to use a “Digital Input” type point.
Pump status, damper end switch
What is “Proportional Band”?
The range of control surrounding a set-point
What is an economizer cycle on an HVAC system?
Allows the use of OSA to save energy.
How is space static pressure controlled in a VAV system?
Modulating the return air via return air dampers, return air fan inlet vanes or return air fan speed control.
Describe how a direct acting thermostat functions.
On an increase of temp there is a corresponding increase in signal from the t-stat to the controlled system.
What are some indications you would see on a BMS system that would tell you that an air handling unit just lost its belt?
Loss of airflow (CFM), motors amperage loss, static pressure loss, High discharge temperature.
What is a Thermistor?
An electrical resistor whose resistance is reduced by heat.
What is a Transducer?
A device that converts pressure into an electrical signal.
H -bridge is used for ?
For bidirectional control of DC motor
Which logic gate has output high if and only if all inputs are High ———?
AND Gate
