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You have the questions. We have the answers. The terms listed here are common sensors terms. This page provides a brief definition of these terms and how they relate to products designed for sensors applications.
| Sensor Glossary |
- Absolute Maximum Ratings - The extreme limits that a product can withstand without damage to the product. Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability.
- Accuracy - The maximum deviation in output from the Ideal Transfer Function measured over the Compensated Flow Range at 25°C [77°F]. Includes all errors due to: Null Output, Flow Non-Linearity, Span Errors, Flow Hysteresis and Non-Repeatability.
- Ambient Temperature - The temperature of the surrounding air.
- Apparent Power - The product of the applied voltage and current in an ac circuit. Apparent power, or volt-amps, is not the true power of the circuit since power factor is not considered in the calculation.
- Auxiliary Power - A power source, other than that producing the measured input quantity, which supplies the power necessary for the correct operation of the transducer.
- Average Responding - The measurement of an AC voltage or current obtained using a DC instrument with a rectifying input circuit that converts AC energy to DC. The meter scale or readout is usually calibrated in terms of the corresponding RMS values, but is accurate only for pure sinewave inputs.
- Burden - In current or potential transformers burden in VA is the maximum load the transformer can support while operating within its accuracy rating.
- Burst Pressure - The maximum pressure that may be applied to any port of the product without causing escape of pressure media. Product should not be expected to function after exposure to any pressure beyond the burst pressure.
- Calibration - Adjustment of a transducer so the output is within a specified range for particular values of the input.
- Clipping Limits - The maximum and minimum limits of signal that the product will output under normal operating conditions.
- Common Mode Pressure - The applied "line" pressure which is common to both ports.
- Compensated Temperature Range - The temperature range (or ranges) over which the product will produce an output proportional to flow within the specified performance limits.
- Compensation - The signal conditioning used to provide a calibrated device whose output closely matches the Ideal Transfer Function. Deviation from the Ideal Transfer Function results in errors which are described by the Total Error Band and Accuracy.
- Delay on Energization - A term describing a mode of operation relative to timing devices. Delay begins when the initiate switch is closed, or on application of power to the input. Same as Delay on Make.
- Delay on Make - Same as delay on energization
- Dielectric Strength - The continuous voltage a dielectric can withstand without deteriorating.
- Effective Power - In ac measurements, effective power (measured in watts) equals the product of voltage, current and power factor (the cosine of the phase angle between the current and the voltage).
- Flow Hysteresis - The maximum difference between output readings when the same flow is applied consecutively, under the same operating conditions, within the specified Operating Flow Range.
- Flow Non Linearity - The maximum deviation of product output from a straight line fitted to the output measured over the specified Operating Flow Range.
- Full Scale Span (FSS) - The algebraic difference between output signals measured at the upper and lower limits of the Operating Flow Range.
- Hysterisis - An error resulting from the inability of an electrical signal or mechanical system to produce identical readings or position when approached slowly from either direction. Also referred to as dead-band.
- Ideal Transfer Function - Mathematically, the ideal Transfer Function is a straight line, which is independent of temperature, passing through the ideal Offset with a slope equal to the ideal Full Scale Span over the Operating Flow Range. See Transfer Function.
- Impedance - The opposition in an electrical circuit to the flow of alternating (AC) current. Impedance consists of ohmic resistance ( R ), inductive reactance (XL), and capacitive reactance (XC).
- Input Impedance - The electrical impedance measured across the input terminals of the product (as presented to the excitation source, with the output terminals open circuited).
- Inrush - The initial surge of current through a load when power is first applied. Lamp loads, induction motors, solenoids, contactors, valves, and capacitive loads all have inrush currents higher than the normal running or steady state currents. Resistive loads, such as heater elements, have no inrush.
- Isolation - To be electrically separate. A measure of the strength of the dielectric providing the electrical division or separation.
- Laminar Flow - Flow condition when a gas flows in smooth parallel layers without causing turbulence.
- Linearity - A measure of departure from straight-line response in the relationship of two quantities, where the change in one is directly proportional to a change in the other. Normally epressed as a maximum percentage.
- Mass Air Flow - Mass flow is a dynamic mass/rate unit measured in grams/minute. By referencing a volumetric flow to a standard temperature and pressure, an exact mass flow (g/min) can be calculated from volumetric flow. It is common in the industry to specify mass flow in terms of volumetric flow at standard (reference) conditions. In accordance with these standards, Honeywell mass flow sensors are specified as having volumetric flow at calibration reference conditions of 760 Torr and 0°C [32°F].
- Maximum Flow - The maximum flow which may safely be applied to the product for it to remain in Specification once flow is returned to the Operating Flow Range. Exposure to higher flows may cause permanent damage to the product. Unless otherwise specified, this applies to all available flow sensors at any temperature within the Operating Temperature Range.
- Maximum Operating Flow (Fmax) - The upper limit of the Operating Flow Range.
- Maximum Power Consumption - The maximum electrical power consumed in normal operation of the product, dependent upon the Supply. See Supply Voltage and Supply Current.
- Minimum Operating Flow (Fmin) - The lower limit of the Operating Flow Range.
- Null Accuracy - The maximum deviation in measured Offset at Reference Temperature relative to the ideal (or target) Offset as determined from the Ideal Transfer Function. See Thermal Effect on Offset. Also known as Offset Error or Zero Point Accuracy.
- Null Output - The output of the sensor when no flow (zero flow) is applied to the sensor. Also known as Offset or Zero.
- Offset Error - The maximum deviation in measured Offset at Reference Temperature relative to the ideal (or target) Offset as determined from the Ideal Transfer Function. See Thermal Effect on Offset. Also known as Null Accuracy or Zero Point Accuracy.
- Operating Flow Range - The flow range over which the product will produce an output proportional to Flow within the specified performance limits.
- Operating Temperature Range - The temperature range over which the product will produce an output proportional to flow but may not remain within the specified performance limits. See Compensated Temperature Range.
- Output Impedance - The electrical impedance measured across the output terminals of the product (as presented to an external circuit).
- Phase Angle - The difference in time by which an alternating signal lags or leads another signal. Phase angle may be a measure of power factor when used to indicate the relationship of a voltage to current signal for a non-resistive load. Phase angle may also be used to measure the different in phase between the primary and secondary of an current or voltage transformer.
- Range - Nominal operating limits, specified by the lowest calibration point to the highest calibration point.
- Ratios - The relationship between the primary input value divided by the secondary output value. For example: a current transformer that has a primary input value of 100 Amps and a secondary value of 5 Amps will have a Current Ratio of 100:5 and a Turns Ratio of 20:1. It is important to use the term Current Ratio for most applications because it defines the current handling capacity of wire used in the secondary winding. The Turns Ratio only refers to the winding ratio and does not define the current handling capacity of the either primary or secondary windings.
- Reference Temperature - The temperature used as a reference in measuring product performance. Typically 25 ±2°C.
- Repeatability - The maximum difference between output readings when the same flow is applied consecutively, under the same operating conditions, within the specified Operating Flow Range. See Flow Hysteresis and Thermal Hysteresis.
- Response Time - Time taken for output of the product to change from 10% to 90% of Full Scale Span in response to a step change in input flow from the specified Minimum to Maximum Operating Flow.
- RMS - The effective value of alternating current or voltage. The RMS value equates an ac signal to a dc signal which provides the same power transfer.
- Sensitivity - The ratio of output signal change to the corresponding input Flow change. Sensitivity is determined by computing the ratio of Full Scale Span to the specified Operating Flow Range. Also known as Slope.
- Sink Current - The maximum current an amplified circuit can accept ("sink") on its output pin and still remain within the specified performance limits.
- Source Current - The maximum current an amplified circuit can supply ("source") on its output pin and still remain within the specified performance limits.
- Span Error - The maximum deviation in measured Full Scale Span at Reference Temperature relative to the ideal (or target) Full Scale Span as determined from the Ideal Transfer Function. See Thermal Effect on Span.
- Stability - The ability of a sensor to retain its performance characteristics with time.
- Standard Conditions - Unless otherwise specified, standard conditions refer to a temperature of 0°C [32°F] and pressure of 101.325kPa (760 Torr).
- Storage Temperature Range - The temperature range over which the product may safely be exposed without excitation or Flow applied. Under these conditions, the product will remain in specification after excursion to any temperatures within this range. Exposure to temperatures outside this range may cause permanent damage to the product.
- Supply Current - Corresponds to the current drain on the supply terminal, dependent upon the Supply Voltage.
- Supply Voltage - Corresponds to the voltage provided on the supply terminal to produce a meaningful output.
- Supply Voltage - Operating Limits - The range of voltage excitation which can be supplied to the product to produce an output which is proportional to Flow, but due to Supply Voltage Ratiometricity errors may not remain within the specified performance limits.
- Supply Voltage - Ratiometric Limits - The range of voltage excitation required by the product to remain within the specified performance limits for Supply Voltage Ratiometricity.
- Supply Voltage Ratiometricity - The maximum deviation in ratiometric output of the product (Output divided by Supply Voltage) resulting from a voltage excitation which is different from the Reference Supply Voltage but remaining within the Supply Voltage Ratiometric Limits.
- Thermal Effect on Offset - The maximum deviation in Offset due to changes in temperature over the Compensated Temperature Range, relative to Offset measured at Reference Temperature.
- Thermal Effect on Span - The maximum deviation in Full Scale Span due to changes in temperature over the Compensated Temperature Range, relative to Full Scale Span measured at Reference Temperature.
- Thermal Hysteresis - The maximum difference between output readings when the same temperature is reached consecutively, under the same operating conditions, with temperature approaching from opposite directions within the specified temperature range.
- Total Error Band (TEB) - The maximum deviation in output from Ideal Transfer Function over the entire Compensated Temperature and Flow Range. Includes all errors due to: Offset, Full Scale Span, Flow Hysteresis, Flow Repeatability, Thermal Effect on Offset, Thermal Effect on Span and Thermal Hysteresis.
- Transfer Function - The equation which defines the output of the product as a function of Flow over the Operating Flow and Temperature Ranges. See Ideal Transfer Function.
- True RMS Amps - The effective value of an ac signal. For an amp signal, true RMS is a precise method of stating the amp value regardless of waveform distortion. An ac measurement which is equal in power transfer to a corresponding dc current.
- True RMS Volts - The effective value of an ac signal. For a voltage signal, true RMS is a precise method of stating the voltage value regardless of waveform distortion. An ac measurement which is equal in power transfer to a corresponding dc voltage.
- VA - The product of the RMS voltage applied to a circuit and the RMS current, in amperes, flowing through it.
- Volumetric Flow - The volume of gas that passes through a given surface per unit time. Honeywell sensors use a standard temperature 0°C [32°F] and standard pressure of 760 Torr. See Standard Conditions.
- Wetted Materials - Materials used in the product which may come into direct contact with measured gases applied to the sensor port(s).
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