Actuator

A mechanism to activate process control equipment by use of pneumatic, hydraulic, or electronic signals; for example, a valve actuator for opening or closing a valve to control the rate of fluid flow.  

 

Proportional band  

The range of values of the controlled variable that will cause a controller to operate over its full range.

 

Setting range of the manipulated variable  

Range of possible variation of the manipulated variable: Overall: 0 to 1 or 0 to 100%, in particular: for example from 0 to 20mm valve stroke.

 

Chain Control  

Combination plant regulated and the regulator (or control system) with autonomous operation

 

CDZ  

Direct expansion air conditioner.

 

Command

One or more input quantities that influence other output variables in a system of open-chain.

 

Control behavior  

Graphic representation in the steady state between the physical quantity x and the set control signal y.

 

Dynamic behavior  

Performance of variations between the output and input variables as a function of time.

 

Behavior over time  

Representation in the time of the control signal to an incoming changes.

 

Static behavior  

Performance of variations between the outgoing and incoming quantities in equilibrium  

 

ON/OFF

 (See FAQ)

 

Time constant Ts

Characteristic of the system.

 

Step function  

Quick change of the input signal of a magnitude (typically the set-point or variable)

 

Disturbance quantity  

External greatness that determines changes on the controlled variable ((Examples: sunlight, heat outside and so on.)

 

Controlled variable  

The quantity or condition that is measured and controlled. (eg temperature, humidity, pressure, etc.). 

 

Regulated plant  

Is a system where a variable should be set at a level determined by the regulator in the presence of unpredictable disturbances.  

 

Regulating device  

Final element of the chain of control that acts on the manipulated variable as a stream of energy or its quantity (eg valve).    

 

RAD  

Damper for the expulsion of air in the rectifiers room.

 

Regulator

An instrument (or group of devices) that continuously measures the value of a variable quantity or condition and then automatically acts on the controlled equipment to correct any deviation from a desired preset value    

 

Regulation  

Is the set of operations designed to make continuous measurements of the controlled value and comparison with the specified value (set point) the result of which influences the manipulated variable in order to maintain the set-point.  

 

Step response  

The behavior of a system when its input signal is zero before a certain time and is equal to a constant nonzero value after this time.    

 

Control deviation ("error"): Xw  

A signal obtained by comparing the output (w) of a control system with the input , which is used to diminish the difference between them x-w= Xw   

 

SEAI  

Internal air exhaust damper (gravity).

 

TA  

Ambient temperature    

 

TE  

External temperature.    

 

Delay Time  

The amount of time by which the arrival of a signal is retarded after transmission through physical equipment or systems.    

 

Dead Time  

The time interval between a change in the input signal to a process control system and the response to the signal.    

 

TSA

Room temperature thermostat.    

 

TSE

Over temperature thermostat.        

 

Actual value  

Is the value assumed instantaneous physical quantity measured by the probe.   

 

VNT FC  

Free-cooling fan.    

 

VNT RAD

Fan ejection rectifiers room rectifiers.    

 

VNT SE  

Fan power station [SE].