SEE "NORMALLY CLOSED"

SEE "NORMALLY OPEN"

STANDS FOR NATIONAL BUREAU OF STANDARDS

STANDS FOR NATIONAL ELECTRIC CODES

STANDS FOR NATIONAL ELECTRICAL MANUFACTURERS' ASSOCIATION

A DIRECT DIGITAL CONTROL (DDC) SYSTEM DEVELOPED BY BARBER-COLMAN CO. (SIEBE CO.) THAT PROVIDES COMPLETE HVAC-BUILDING AUTOMATION

STANDS FOR THE NATIONAL FIRE PROTECTION ASSOCIATION

A CONDITION GENERALLY ASSOCIATED WITH THERMOSTATS, THAT IS WHEN THE SETPOINT OF THE THERMOSTAT IS SET/SHIFTED TO A LOWER TEMPERATURE DURING UNOCCUPIED HOURS, ESPECIALLY DURING THE HEATING SEASON

GENERALLY ASSOCIATED WITH THERMOSTATS, WHEN THE SETPOINT IS SET/SHIFTED TO A HIGHER TEMPERATURE DURING UNOCCUPIED HOURS, ESPECIALLY DURING THE COOLING SEASON

STANDS FOR NATIONAL INSTITUTE FOR STANDARDS AND TECHNOLOGY.

AN UNWANTED COMPONENT OF A SIGNAL OR VARIABLE

A TERM/CONDITION THAT APPLIES TO A CONTROLLED DEVICE WHICH CLOSES WHEN EITHER A POWER FAILURE OCURRS, OR WHEN CONTROL PRESSURE IS REMOVED

A TERM/CONDITION THAT APPLIES TO A CONTROLLED DEVICE THAT IS OPEN WHEN ALL OPERATING FORCE IS LOST, SUCH AS IN A POWER FAILURE

STANDS FOR NATIONAL PIPE THREAD

STANDS FOR OUSIDE DIAMETER

STANDS FOR OUTDOOR AIR

A CONTROL MODE THAT IS USED TO HEAT OR COOL BUILDINGS WHILE THEY ARE OCCUPIED

THE AMOUNT OF DIFFERENCE BETWEEN CONTROL POINT AND SETPOINT IN A PROPORTIONAL CONTROL SYSTEM

THE ADJUSTMENT TO THE ACTUAL INPUT TENMPERATURE AND TO THE TEMPERATURE VALUES THAT THE CONTROLLER USES FOR DISPLAY & CONTROL

USED TO MEASURE ELECTRICAL RESISTANCE

SEE "CONTROL, ON/OFF"

A CONTROL SYSTEM WITH NO SENSORY FEEDBACK

STANDS FOR OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION

AN ACTION CAUSED IN RESPONSE TO THE DIFFERENCE BETWEEN SETPOINT AND PROCESS VARIABLE

GENERALLY PLUG-IN DEVICES SUCH AS RELAYS THAT PROVIDE POWER HANDLING TO ENABLE PROCESS CONTROL; MODULES CAN BE EITHER BINARY (ON/OFF) OR ANALOG (CONTINUOUSLY VARIABLE) FOR CURRENT LOOP CONTROL

THE CONDITION WHEN TEMPERATURE EXCEEDS SETPOINT DUE TO INITIAL POWER-UP OR PROCESS CHANGES

AN ATMOSPHERE THAT CONTAINS SIGNIFICANT AMOUNTS OF ACTIVE OXYGEN.

STANDS FOR "PROPORTIONING" CONTROL

ANY SPECIFIC CHARACTERISTIC OF A DEVICE/CONTROL

ADDITION OF ALL THE BITS IN A WORD IS COMPARED TO THE PARITY BIT (EVEN OR ODD). IF THEY ARE BOTH THE SAME, THE DATA IS ACCEPTED, OTHERWISE IT IS REJECTED.

STANDS FOR PROPORTIONAL BAND

STANDS FOR PRINTED CIRCUIT BOARD

STANDS FOR "PROPORTIONING CONTROL WITH RATE ACTION

THE MAXIMUM ELECTRICAL LOAD OR THERMAL LOAD REACHED DURING A SPECIFIC PERIOD OF TIME

GENERALLY COMMON WITH THE ADJUSTMENT OF RECEIVER CONTROLLERS WHICH DETERMINES THE EFFECT OF THE RESET SIGNAL OF THE SECONDARY TRANSMITTER AS A PERCENTAGE (%) OF THE SIGNAL OF THE PRIMARY TRANSMITTER

A RESIN BASED TYPE OF HARD RUGGED PLASTIC THAT IS USUALLY USED IN INSULATING. PHENOLIC IS THE SAME AS BAKELITE.

STANDS FOR "PROPORTIONING CONTROL WITH AUTO-RESET"

STANDS FOR "PROPORTIONING CONTROL WITH AUTO-RESET AND RATE"

THE NOBLE METAL GENERALLY USED IN TYPES R & S THERMOCOUPLES

CONTROLS THAT RUN ON LOW-PRESSURE COMPRESSED AIR

THE MAXIMUM AMOUNT OF PRESSURE (PSI) THAT WILL COMPLETELY COMPRESS AN ACTUATOR'S SPRING TO COMPLETE ITS STROKE. EXAMPLE: AN ACTUATOR WITH A SPRING RANGE OF 3 TO 8 PSI; "8" IWOULD BE CONSIDERED THE "FINISH POINT".

CONTROL OUTPUT THAT UTILIZES TWO RELAYS TO CONTROL AN ELECTRIC OR MOTORIZED ACTUATOR MOTOR

A BALANCING BRIDGE WHICH IS USED TO MEASURE VOLTAGE; ALSO THROUGH THE USE OF A RESISTOR IS USED TO CONTROL A CIRCUIT(S)

STANDS FOR PARTS PER MILLION

SEE "PULSES PER REVOLUTION"

THE DIFFERENCE IN PRESSURE BETWEEN TWO POINTS IN A FLOW SYSTEM. THE PRESSURE DIFFERENCES ARE USUALLY CAUSED BY FRICTIONAL RESISTANCE TO FLUID FLOW IN A CONDUIT, FILTER, OR OTHER FLOW SYSTEM

THE OUTER LOOP IN A CASCADE SYSTEM

ANY CHARACTERISTIC OR MEASURABLE ATTRIBUTE WHOSE VALUE CHANGES WITH CHANGES IN PREVAILING CONDITIONS; SOME COMMON VARIABLES ARE TEMPERATURE, LEVEL, PRESSURE, FLOW, HUMIDITY, ECT.

STANDS FOR "PROGRAMMABLE READ ONLY MEMORY".

THE CHANGE IN INPUT THAT IS REQUIRED TO PRODUCE A FULL RANGE CHANGE IN OUTPUT DUE TO PROPORTIONAL CONTROL ACTION

A TUBE WHICH IS CLOSED AT ONE END IN WHICH A THERMOCOUPLE IS INSERTED INTO IN ORDER TO PROTECT THE THERMOCOUPLE FROM EXCESSIVE HEAT OR ABRASIVE MEDIUM; PROTECTION TUBES COME IN MANY VARIETIES & MATERIALS. SEE  PROTECTION TUBE SELECTIONS STARTING ON Pg.

STANDS FOR POUNDS PER SQUARE INCH ABSOLUTE

STANDS FOR POUNDS PER SQUARE INCH DIFFERENTIAL

STANDS FOR GAUGE PRESSURE WHICH IS THE AMOUNT OF PRESSURE ABOVE ATMOSPHERIC PRESSURE

STANDS FOR POUNDS PER SQUARE INCH STANDARD

MEASURES RELATIVE HUMIDITY

THE DEVIATION IN ELECTRICAL DEGREES OF THE PULSE WIDTH FROM THE IDEAL VALUE OF 180 DEGREES.

THE NUMBER OF PULSE INTERVALS OF AN OUTPUT SIGNAL FOR EACH REVOLUTION OF THE INPUT SHAFT.

STANDS FOR PRINTED WIRE BOARD

TYPICALLY MEASURES HIGH TEMPERATURES UPTO 2,000 DEGREES F.

SEE "THERMOCOUPLE" OR "RTD"

THE TERM FOR TWO (2) NEARBY IDENTICAL PERIODIC SIGNALS WHEN THE PHASE DISPLACEMENT IS NOMINALLY 90 ELECTRICAL DEGREES.