Transcript load cell errors

Practical experiences
with OIML R60
Sascha Mäuselein
Oliver Mack
SIM MWG11 – Load Cells Tests by OIML R60
Buenos Aires, June 2010
Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Buenos Aires, June 2010
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Excitation voltage – creep
Excitation voltage
5V
Excitation voltage
10 V
Z = 5000
Z < 3000
Creep, DR and error limit of a C3-LC (300g)
at 40°C as function of time
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Excitation voltage – load cell errors
Excitation voltage
5V
Excitation voltage
10 V
Load cell errors of a 600 kg LC (C5)
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Force introduction – material
Force introduction made of
stainless steel
Force introduction made of
aluminium
Y = 20000
Y = 4500
Influence of temperature on MDLO in v for a C3 LC and
mpe for Y = 20000 as function of ambient temperature
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Buenos Aires, June 2010
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Force introduction – types
Force introduction via
platform
Force introduction via
suspension gear
n = 1500
n = 3000
Load cell errors of a 8kg single point LC (C3)
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Buenos Aires, June 2010
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Force introduction – embodiment
Load cell errors of a LC for different punctual force introductions
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Buenos Aires, June 2010
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Buenos Aires, June 2010
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Eccentricity
Mpe for class C3 and load cell errors in units of v
as function of load for a 8 kg LC
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Stability of temperature
Zero signal of a single point LC (C3, 140kg) in units of v
as function of time at 40°C and 85%rH
Variation of zero signal of 4 v
at a variation of temperature of 2°C
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Air flow
Zero signal of a single point LC (C3, 140kg) in units of v
as function of time at 41°C and 85%rH
Variation of zero signal of 0,5 v
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Buenos Aires, June 2010
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Air flow
Reduction of
air flow by a tent
Zero signal of a single point LC (C3, 140kg) in units of v
as function of time at 41°C and 85%rH; LC in tent
Variation of zero signal of 0,02 v
 Reduction by a factor of 25
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Table of contents
• Excitation voltage
• Force introduction
• Material
• Types
• Embodiment
• Eccentricity
• Stability of temperature
• Air flow
• Settling- and Drying-effects
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Buenos Aires, June 2010
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Settling- and drying-effects
1. first creep measurement at 20°C;
after delivery
2. first creep measurement at 40°C
-> failed
SIM MWG11 – Load Cells Tests by OIML R60
-> failed
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Settling- and drying-effects
3. first creep measurement at -10°C
4. repeat of creep measurement at 20°C
-> passed
SIM MWG11 – Load Cells Tests by OIML R60
-> passed
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Settling- and drying-effects
5. repeat of creep measurement at 40°C 6. further creep measurement at 40°C
after 3 days storing at 40°C
-> passed
-> failed
3 days storing
at 40°C
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Table of contents
• Excitation voltage
->
Creep and LC error
• Material
->
Zero point (Y)
• Types
->
LC error
• Embodiment
->
LC error
• Eccentricity
->
LC error
• Stability of temperature
->
Zero signal, LC signal
• Air flow
->
Zero signal, LC signal
• Force introduction
• Settling- and Drying-effects ->
SIM MWG11 – Load Cells Tests by OIML R60
Creep
Buenos Aires, June 2010
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Thank you for your attention
Practical experiences
with OIML R60
Sascha Mäuselein
Oliver Mack
SIM MWG11 – Load Cells Tests by OIML R60
Buenos Aires, June 2010