STANDS FOR RANDOM ACCESS MEMORY

STANDS FOR "RANDOM ACCESS MEMORY"

SEE "SETPOINT, RAMPING"

AN ACTION THAT SENSES THE RATE OF CHANGE OF TEMPERATURE AND COMPENSATES TO MINIMIZE OVERSHOOT; ALSO "DERIVATIVE"

THE DERIVATIVE FUNCTION OF A PROCESS TEMPERATURE CONTROLLER

THE TIME INTERVAL OVER WHICH THE SYSTEM TEMPERATURE IS SAMPLED FOR THE DERIVATIVE FUNCTION

RESISTIVE / CAPACITIVE CIRCUIT, USED IN DIGITAL CIRCUITS TO ESTABLISH A TIME BASE.

TO MAINTAIN A CONTROLLED VARIABLE AT OR NEAR ITS RANGE OR SETPOINT, DEPENDING UPON THE DEVICE

WHEN HEAT IS ADDED TO COOLED OR HUMIDIFIED PRIMARY AIR OR RECIRCULATED ROOM AIR

AN OPEN-LOOP GAIN DETERMINED WITH ALL OTHER MANIPULATED VARIABLES CONSTANT, DIVIDED BY THE SAME GAIN DETERMINED WITH ALL OTHER CONTROLLED  VARIABLES CONSTANT

AN ELECTROMECHANICAL DEVICE THAT COMPLETES OR INTERRUPTS A CIRCUIT BY PHYSICALLY MOVING ELECTRICAL CONTACTS INTO CONTACT WITH EACH OTHER

A SOLID STATE SWITCHING DEVICE THAT COMPLETES OR INTERRUPTS A CIRCUIT ELECTRICALLY WITH NO MOVING PARTS AT ALL

SEE "EXHAUST DAMPER"

TO RESET OR TO "CLEAR"; AUTOMATICALLY ELIMINATES OFFSET OR DROOP BETWEEN SETPOINT AND ACTUAL PROCESS TEMPERATURE; ALSO "INTEGRAL"

SEE "RTD"

SEE "RC"

A SMALL FITTING-LIKE PART THAT CHANGES THE VELOCITY PRESSURE OF THE AIR LINE TO STATIC PRESSURE. THE GENERAL SIZE OF RESTRICTORS ARE 0.005" OR 0.0075", AND CAN BE FOUND ON PG#_____ OF THIS CAPP/USA CATALOG

ALLOWS THE TRANSMISSION OF A MILLIAMP SIGNAL CORRESPONDING TO THE PROCESS VARIABLE, TARGET SETPOINT, OR ACTUAL SETPOINT TO ANOTHER DEVICE SUCH AS A CHART RECORDER

AIR THAT IS BEING RETURNED FROM THE HEATED OR AIR-CONDITIONED SPACE/ROOM, BACK  TO THE HEATER OR AIR CONDITIONER

A DECREASE IN THE MEDIA THAT IS BEING SENSED CAUSES AN INCREASE IN OUTPUT

STANDS FOR RADIO FREQUENCY

VARIABLE RESISTOR

STANDS FOR ROOT MEAN SQUARED

STANDS FOR READ ONLY MEMORY

A PACKEGED HVAC UNIT WHICH IS SPECIFICALLY DESIGNED TO BE MOUNTED ON THE ROOFTOP OF A BUILDING. ROOFTOP UNITS RANGE IN SIZE FROM FROM SMALL-SINGLE ZONE UNITS, TO LARGE CAPACITY UNITS WHICH SUPPLY AIR TO MULTIPLE VAV TERMINALS, ETC.

STANDS FOR ROTATION

STANDS FOR REVOLUTIONS PER MINUTE

STANDS FOR ROTARY SCALE

STANDARDS RECOMMENENDED BY THE EIA FOR SERIAL DATA TRANSMISSION BETWEEN DIGITAL DEVICES AND PROCESS INSTRUMENTS.

STANDS FOR RESISTANCE TEMPERATURE DETECTOR; AN RTD IS A RESISTIVE SENSING DEVICE THAT DISPLAYS RESISTANCE VS. TEMPERATURE CHARACTERISTICS, AND POSITIVE TEMPERATURE COEFFICIENT. SEE A WIDE-VARIETY OF RTD's STARTING ON Pg.____ OF THIS CATALOG

THE TOTAL AMOUNT OF RUNNING HOURS WHICH AN HVAC SYSTEM HAS BEEN RUNNING SINCE EITHER ITS INSTALLATION, OR ITS LAST PREVENTATIVE MAINTENANCE DATE

STANDS FOR THE SCIENTIFIC APPARATUS MAKERS ASSOCIATION.

STANDS FOR "SILICON CONTROLLED RECTIFIER".

THE INNER LOOP OF A CASCADE SYSTEM

SENSIBLE HEAT IS HEAT THAT CHANGES ONLY THE TEMPERATURE OF THE AIR WITHOUT A CHANGE IN THE MOISTURE CONTENT.  GENERALLY A CHANGE IN DRY-BULB THERMOMETER READINGS USUALLY INDICATE CHANGES IN SENSIBLE HEAT

SEE "IMMERSION SENSOR"

THE SENDING OR RECEIVING OF BINARY CODED DATA TO A SUPERVISORY DEVICE SUCH AS A PC (PERSONAL COMPUTER) OR PLC (PROGRAMMABLE LOGIC CONTROLLER)

THE VALUE OF A CONTROLLED VARIABLE THAT THE CONTROL/CONTROLLER IS CURRENTLY ACTING UPON

THE NUMBER OF UNITS DIFFERENCE BETWEEN THE CURRENT PROCESS VARIABLE AND THE SETPOINT

A SETPOINT THAT IS DETERMINED BT THE RAMP FUNCTION OF A CONTROLLER WHERE OVER TIME THE CONTROLLER VARIABLE REACHES A DESIRED VALUE

THE END POINT OF THE RAMPING/RAMP FUNCTION

WHEN THE SIGNAL IS LOST---IN SERIAL COMMUNICATIONS

SEE "SPDT"

AN OUTPUT ALGORITHM THAT UTILIZES A SLIDEWIRE FEEDBACK SIGNAL TO DETERMINE THE ACTUAL POSITION OF THE ACTUATOR/MOTOR BEING CONTROLLED

SEE "RELAY ( SOLID STATE)"

THE DIFFERENCE BETWEEN THE START  & FINISH POINT OF A RANGE. FOR EXAMPLE: A RANGE OF 50 DEG. TO 100 DEG. = SPAN OF 50 DEG.; 60 TO 9 VOLTS = SPAN OF 3 VOLTS; 3 TO 8 PSI = SPAN OF 5 PSI.

SPDT OR SINGLE-POLE/DOUBLE-THROW IS A SWITCHING ACTION THAT "MAKES" ONE CIRCUIT IMMEDIATELY UPON BREAKING THE OTHER

A SPRING MECHANISM INSIDE  AN ACTUATOR WHICH UPON A LOSS OF POWER (POWER FAILURE) IMMEDIATELY WILL DRIVE THE ACTUATOR EITHER TO AN OPEN OR CLOSED POSITION

A REPETITIVE WAVEFORM, USUALLY A.C., WHOSE SHAPE IS ESSENTIALLY SQUARE OR RECTANGULAR USUALLY WITH AN EQUAL DUTY CYCLE.

STANDS FOR STEAM SUPPLY, AND/OR THE ALLOY STAINLESS STEEL

A.D.C. ON/OFF SIGNAL OUTPUT FOR CONTROLLING A SOLID STATE RELAY

THE SET-UP OF TWO ANALOG OUTPUTS, WHERE ONE ANALOG OUTPUT VARIES ITS SIGNAL OVER A PORTION OF THE PID OUTPUT RANGE, AND THE SECOND ANALOG OUTPUT THEN VARIES ITS SIGNAL OVER THE REMAINDER OF THE PID OUTPUT RANGE

A CONTROL/CONTROLLER THAT DOES NOT REQUIRE SUPPORT FROM ANOTHER DEVICE OR SYSTEM

UNDESIRABLE CURRENT RESULTING FROM THE DISCHARGE OF ELECTROSTATIC ENERGY

A UNIQUE IDENTIFIER ASSIGNED TO A DEVICE OR DEVICES FOR COMMUNICATIONS PURPOSES

REGULATING THE AIR PRESSURE INSIDE OF A DUCT OR A ROOM IN RELATION TO A REFERENCE PRESSURE. GENERALLY CONTROLLED IN TERMS OF INCHES OF W.C. (WATER COLUMN)

LAYERS OF AIR AT DIFFERENT TEMPERATURES OF DIFFERENT VELOCITIES FLOWING THRU A DUCT OR PLENUM

THE LINEAR DISTANCE IN WHICH AN ACTUATOR SHAFT MOVES