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Phase I - SpecificationRMT Sales Training - 05 /98
PHASE I
Agenda:Agenda:• Interpretation of transmitter specification
• Physical• Functional• Performance• Dynamic performance
• Types of error• Performance measurement
Fundamentals of Process ControlFundamentals of Process Control
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Phase I - SpecificationRMT Sales Training - 05 /98
Sensor interchangeability error
ORStatic pressure effect
ERROR !
Ambient temperature effect
Reference accuracy
4 SOURCES OF ERROR4 SOURCES OF ERROR
Drift over time(stability)
- we need to review Performance Requirements
What Transmitter ???What Transmitter ???
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Phase I - SpecificationRMT Sales Training - 05 /98
Physical SpecificationsPhysical Specifications
– Materials of Construction:Materials of Construction:• Housing materials, Process flange materials, Paints, bolts, etc.
– Process/Electrical Connection:Process/Electrical Connection:• Dimensions, thread types, and center-to-center dimensions of the
process connections.– Weight:Weight:
• Lists the weight of the instrument.– Product Specific Physical Specifications:Product Specific Physical Specifications:
• Example: Type of fill fluid, LCD options, Transient protector option, etc.
Describe the Physical Make-Up of the Transmitter.Describe the Physical Make-Up of the Transmitter.
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Phase I - SpecificationRMT Sales Training - 05 /98
Functional SpecificationsFunctional Specifications
Range LimitsRange Limits• Upper Range Limit (URL)
» The highest quantity that a device can be adjusted to measure• Lower Range Limit (LRL)
» The lowest quantity that a device can be adjusted to measure• Upper Range Value (URV)
» 20 mA operating point (100% reading)• Lower Range Value (LRV)
» 4 mA operating point (0% reading) SpanSpan
• URV - LRV
Describes the Environment within which the transmitter Describes the Environment within which the transmitter can operator & still meet its Performance Specification.can operator & still meet its Performance Specification.
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Phase I - SpecificationRMT Sales Training - 05 /98
Functional SpecificationsFunctional Specifications
Example of Range limits & Spans:Example of Range limits & Spans:
0- 100 psi + 100 psi
LRL URL
A Differential Pressure Transmitter
Sensor Limits
TransmitterCalibrated / Ranged:
4 mALRV
20 mAURV
30 psi 80 psi
CalibratedSpan =50 psi
0%Reading
100%Reading
Turndown ?
URL / Cal. Span = 100 / 50 2:1
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Phase I - SpecificationRMT Sales Training - 05 /98
Rangeability / TurndownRangeability / Turndown• Allowable range of spans through which errors are of an acceptable value
» Min. Span up to Span = URL» Ex) Turndown = 10:1 & URL = 500 psi
Min. Span = URL / 10 = 50 psi
OutputsOutputs• The type of signal representing the process variable that is delivered by the transmitter
» Eg. 4-20 mA, 3-15 psi, Digital
ServiceService• Describes the process that be measured. Eg. Liquid, gas, vapor
Functional SpecificationsFunctional Specifications
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Phase I - SpecificationRMT Sales Training - 05 /98
Hazardous LocationHazardous Location• Describes the types of hazardous location that the
transmitter is certified for use within. Eg. Class 1, Div 1and 2, Groups B,C
• Approvals
Functional SpecificationsFunctional Specifications
Hazardous Area Risk of FIRE & EXPLOSIONZone 0 HighZone 1 IntermediateZone 2 Occasional
Weather proof Level of IINGRESS PPROTECTIONIP65 / 66 1st digits 6 represent Dust Tight.IP67 / 68 2nd digits represent level of protection
against water. The higher the value thethe better the level of protection.
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Phase I - SpecificationRMT Sales Training - 05 /98
Danger of FIRE and EXPLOSION in HAZARDOUS AREAS
Zone Safety approach Letter Code Authority
Intrinsically Safe0 Electronics safe
Flameproof1 Explosion retained
Flame quenched
Non Incendive2 No arcs,sparks or
hot surfaces
Functional SpecificationsFunctional Specifications
I
E
N
19
5
6
CENELEC(Europe)
FM(USA)
CSA(Canada)
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Phase I - SpecificationRMT Sales Training - 05 /98
Functional SpecificationFunctional Specification
– SST Certification Tag Provided• Explosion Proof
• E5 (FM)• E8 (CENELEC / CESI)
• Intrinsic Safety• I1 (BASEEFA / CENELEC)
• Non-Incendive• N1 (BASEEFA / CENELEC)
• Non-Incendive + Intrinsic Safety• I5 (FM)
• Explosion Proof + Intrinsic Safety• C6 (CSA)• K5 (FM)• K8 ( FM + CSA)• K6 (CSA = CENELEC)
Examples of Approvals for TransmittersExamples of Approvals for Transmitters
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Phase I - SpecificationRMT Sales Training - 05 /98
Functional SpecificationsFunctional Specifications
Normal Operating Range
mA
Hardware Alarm
Process Variable Out of Range
21.753.8
2020.8
43.9
Failure Mode AlarmFailure Mode Alarm• If self-diagnosis detects a gross transmitter failure, the
analog signal will be driven to low output /high output to alert the user
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Phase I - SpecificationRMT Sales Training - 05 /98
Functional SpecificationsFunctional Specifications
Power SupplyPower Supply
• Describes the power that is required to operate the transmitter which will coincide with the output selected.
Load limitationLoad limitation
• The maximum load that can be present in the loop for the transmitter to operate over its full output range for a given power supply.
Voltage
Lo
ad
At voltage Vs :
At no load min. voltage is 12 V dcThe max. voltage should not exceed 45 V dc
RL is the max. load possible
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Phase I - SpecificationRMT Sales Training - 05 /98
Functional SpecificationsFunctional Specifications
Static Pressure LimitsStatic Pressure Limits• Level of static(line) pressure that a transmitter can be
exposed to in which the transmitter will function within specifications
Overpressure LimitsOverpressure Limits• Level to which only one side of a pressure transmitter
can be exposed to without causing damage Proof (burst) pressureProof (burst) pressure
• Pressure to which transmitter can retain fluid without flying parts
Pressure LimitsPressure Limits
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Phase I - SpecificationRMT Sales Training - 05 /98
QuizQuiz
1151DP4S
(URL = 150 inH2O, min span = URL/15
Min. Span= _______
Max. Turndown = __________
3051CD3
(Range: 0 -10 to 0 - 1000 inH2O)
Min Span _______
Max. Turndow = __________
Example #2Example #2
10 inH2O
15:1
10 inH2O
100:1
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Phase I - SpecificationRMT Sales Training - 05 /98
Performance SpecificationsPerformance Specifications
Quantify Uncertainty of a Measurement as a Function Quantify Uncertainty of a Measurement as a Function of Changing Ambient & Process Conditions.of Changing Ambient & Process Conditions.
Reference AccuracyReference Accuracy• Defines maximum error at reference conditions
» Zero-based:» 14.73 psia, 68 deg F.» May have limits on material types» Includes effects of linearity, repeatability, hysteresis» Typically expressed as a % of calibrated span
• Ways to express reference accuracy:
» % of URL» % of span» % of reading
Commonly used in Transmitters
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Phase I - SpecificationRMT Sales Training - 05 /98
Performance SpecificationsPerformance Specifications– Transmitters are factory calibrated at room temperature.– If transmitter operates at a different ambient temperature,
the electronics perform differently. – The change in performance can create an error in the
measurement.This error is the This error is the
Ambient Ambient Temperature EffectTemperature Effect
Zero Temperature EffectsZero Temperature Effects» Expressed as a % of URL per some T from
standard conditions Span Temperature EffectsSpan Temperature Effects
» Expressed as a % of Calibrated Span per some T from standard conditions.
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Phase I - SpecificationRMT Sales Training - 05 /98
Performance SpecificationsPerformance Specifications
• The effect on transmitter zero and span due to the application of static (line) pressure
» Applies to differential pressure transmitters only.
» Zero LP Effect: Expressed as % of URL per change in static pressure
» Span LP Effect: Expressed as % of Calibrated Span change in static pressure
Static Pressure EffectsStatic Pressure Effects
Span = 20 psi
At differentLine Pressure
50 psi 30 psi100 psi 80 psi500 psi 480 psi1000 psi 980 psi
Same Flow Rate
However at higher line pressure the sensor is subject to higher stress & therefore may induced error in registering the DP
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Phase I - SpecificationRMT Sales Training - 05 /98
Vibration EffectVibration Effect• The effect upon output is solely due to the vibratory
environment to which the transmitter is subjected.
Power Supply EffectPower Supply Effect• If a transmitter is operated at a different voltage in the
field, then it was calibrated with on the bench, then variations in output (for the same input) can occur.
Performance SpecificationsPerformance Specifications
All transmitters will drift over time , All transmitters will drift over time , compounding error in the point measurementcompounding error in the point measurement
StabilityStability•Change in output given a fixed input as a function of TIME.•Determines calibration frequencies.
»Units of uncertainty are dependent on product type.
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Phase I - SpecificationRMT Sales Training - 05 /98
RFI/EMI EffectsRFI/EMI Effects• Output change as a result of radio or electromagnetic interference.
Potential sources of interference:» Motors, Radios
Mounting positionMounting position– Difference in output when a transmitter is mounted in a position different to
which it was calibrated.
Load EffectLoad Effect– If the total loop should alter, then the output of the transmitter (for the
same process input) may be effected
LinearityLinearity– Maximum deviation from a Straight Line.
Performance SpecificationsPerformance Specifications
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Phase I - SpecificationRMT Sales Training - 05 /98
Repeatability:Repeatability: • Ability to reproduce output reading when same input is
applied under the same conditions, and in the same direction.
Hysteresis:Hysteresis:• The maximum difference in output at any input value,
when the value is approached first with increasing then decreasing input.
Performance SpecificationsPerformance Specifications
Reproducibility:Reproducibility:• The closeness of agreement among repeated measurements
of the output for the same value of the input under the same operating conditions over a period of time, approaching from both directions.
• It includes hysteresis, drift and repeatability.
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Phase I - SpecificationRMT Sales Training - 05 /98
• Acc = ±0.1% of URL
Performance SpecificationsPerformance Specifications
Example #3Example #3
Assuming an input of 80 inH2O:Pressure Transmitters URL = 300 inH2OCalibration: 0-200 inH2OWhat is the maximum error (%) at reading ?
• Accuracy = ±0.1% of reading
0.001 x 300 = 0.3 inH2O
(0.3 / 80) x 100% =±0.375%0.001 x 200 = 0.2 inH2O
(0.2 / 80) x 100% =±0.25%
±0.1%
• Accuracy as specified (±0.1% of span)
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Phase I - SpecificationRMT Sales Training - 05 /98
Performance SpecificationsPerformance Specifications
What is the maximum LP error (%) of an 1151DP4S (URL = 150 inH2O) at 1500 psi static pressure, calibrated 0 to 100 inH2O, measuring 60 inH2O?
What is the maximum LP error (%) of an 1151GP8S measuring 1000 psig?
Example #4Example #4
Given Zero Error = ±0.25% of URL for 2,000 psi & Span Error correctable to ±0.25% of reading per 1,000 psi
(0.0025 x 150 x 0.75) + (0.0025 x 60 x 1.5) =±0.58 psig
Zero error span error total error
N.A
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Phase I - SpecificationRMT Sales Training - 05 /98
What is temperature error (%), expressed in psig, of a 3051CG5 (URL = 2000 psig) , calibrated 0 to 1000 psig in factory at 68°F, measuring 500 psig, at 168 deg F.
What is the minimum amount of error (%) that could be achieved without re-zeroing at temperature?
Performance SpecificationsPerformance Specifications
Example #5Example #5 Given Ambient Temperature Effect per 50°F : ±(0.0125% URL + 0.0625% Span) spans from 1:1 to 10:1 ±(0.025% URL + 0.125% Span) spans from 10:1 to 100:1
(0.000125 x 2000) + (0.000625 x 1000) = ±0.65 psig
0.65 psig x 2 =±1.3 psig
0 psig
100°F
2:1
2:1
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Phase I - SpecificationRMT Sales Training - 05 /98
Dynamic Performance Dynamic Performance
Response Time DefinitionsResponse Time Definitions
Time0
}
T63
63.2%
TcTd– Faster Responding Sensor (Tc)
– Faster Update Rate (Td)
– Optimized Software / Processing (Td)
– Minimal Filtering (Tc)
– Total Response Time (T63)Damping
• Transducer response time
• Signal conversion time (eg. A/D modem)
• Micro-processing time
• adding a delay time
Deadtime (Td): The time before output starts to change.
Time Constant (Tc): The time necessary (after deadtime) for output to reach 63.2% of its final value.
Total Response Time (T63): Deadtime (Td) plus one Time Constant (Tc)
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Phase I - SpecificationRMT Sales Training - 05 /98
Different Types of ErrorsDifferent Types of Errors
Span-ErrorSpan-Error• Difference between
calibrated and ideal span.
4-20 mA OUTPUT
4-20 mA OUTPUT
4-20 mA OUTPUT
Ideal Span0 to 100 inH2O Input
4-20 mA OUTPUT
4-20 mA OUTPUT
4-20 mA OUTPUT
Ideal Span0 to 100 inH2O Input
Zero-ErrorZero-Error– Fixed offset between
true and measured
value.
Total-ErrorTotal-Error• Zero Error plus Span Error.
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Phase I - SpecificationRMT Sales Training - 05 /98
P
F
0 URL
Sensor Curve
Turndown ErrorTurndown Error• Arises when a span less than the Transmitter’s full span is used.
The smaller the calibrated span, the greater the errors over the span.
Different Types of ErrorsDifferent Types of Errors
Turndown Factor 4 : 14095 : 1023
8 : 14095 : 511
4:1
Resolution < 0.1%
Resolution > 0.1%Capacitance to
Digital converter (A/D)
For example:
12 bits Register represent full sensor range
Resolution = 1/4095 < 0.1%
8:1
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Phase I - SpecificationRMT Sales Training - 05 /98
Performance MeasurementPerformance Measurement
Total probable error (TPE)Total probable error (TPE) analysis provides a more accurate picture of how a transmitter can be expected to perform under specific conditions or changes in conditions.
The Root Sum Square(RSS)The Root Sum Square(RSS) method determines the TPE by summing the squares of individual error components, and then taking the square root of the total.
Up = (accuracy2 + temp eff2 + (...eff)2)1/2
where Up = total uncertainty (TPE)
Worse Case ErrorWorse Case Error is the sum of individual error components. This error is unlikely to occur, since all the effects may not take place at the same time.
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Phase I - SpecificationRMT Sales Training - 05 /98
Total Probable ErrorTotal Probable Error
Given:• Accuracy = +/-0.1% of span• Total Temperature Effects = +/-0.5% of span• LP Effects = +/-0.3% of span• Power Supply Effect = +/- 0.010% of span
What is the TPE in (express in psig) if the calibrated span is 3.61 psig?
Example #6Example #6
(0.12 + 0.52 + 0.32 + 0.012) ½ =±0.59%
0.0059 x 3.61 psig = ±0.02 psig
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Phase I - SpecificationRMT Sales Training - 05 /98
TestTest
Select the appropriate term for the following definitions:
(A) Damping (B) Reference Accuracy
(C) Dead-time (D) Time-constant
(E) Response time (F) Repeatability
(G) Stability (H) Span error
(I) Turndown error (J) Zero error
1. An error occurred when the transmitter is used
at a span other than its full span. [ ]
2. Fixed offset between true & measured value. [ ]
3. Time necessary for analog output to reach
63.2% of its final value. [ ]
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Phase I - SpecificationRMT Sales Training - 05 /98
TestTest
4. Deviation in measurement for the same input
approaching from one direction. [ ]
5. Electronic delay circuit to increase transmitter’s
response time. [ ]
6. Limits of error at standard reference conditions. [ ]
7. Time before transducer’s output starts to change. [ ]
8. Transmitter’s drift over time. [ ]
9. Dead-time + Time constant. [ ]
10. Drift in transmitter’s calibrated range. [ ]
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Phase I - SpecificationRMT Sales Training - 05 /98
Answer SheetAnswer Sheet
Enter the answers for the test given in this module and sent one copy to the RMT A/P Trainer in Singapore . Attention to RMT Trainer at Fax : (65) 7708000 or (65) 7770947 or (65) 7770743E-Mail : mohd.rafi@frco.com
RMT Trainer will feedback to you the result & solution
Name: Title:
Company: Date:
Q1 Q6
Q2 Q7
Q3 Q8
Q4 Q9
Q5 Q10
Marks: /10 Marks (%):
Specifications FundamentalSpecifications Fundamental
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