a) A load cell transducer is used to measure the weight of a truck. Full load ca
ID: 2249808 • Letter: A
Question
a) A load cell transducer is used to measure the weight of a truck. Full load capacity of the load cell is about 45,000kg. Attached in this paper is a 2 page datasheet. (Attachment 1). As an engineer, you are required to study the information in the datasheet and extract at least FIVE (5)characteristics (e.g. static characteristics, operating parameters, ratings, etc.) marks)
b) Determine the followings:
i. Calculate the minimum temperature effect on rated output.
ii. Calculate the maximum overload that the load cell is able to measure.
iii. What is mean by IP rating? Further, state the meaning of IP68.
iv. What is the input and output measurement for a load cell, based on the Wheatstone bridge circuit.
DESCRIPTION SPECIAL FEATURES A hermetically sealed load bearing unit operating in compression to produce an analogue output which is proportional to the applied load. Construction is 100% stainless steel, natural finish. 4x50G Surge arresters fitted internally to provide protection against lightning damage. Supplied ready-assembled with gaiters and load buttons for simple installation. Compact design Built to last - robust design Quality assured IP69K ideal for harsh environments Outstanding accuracy & performance Built-in lightning protection Retrofitable design Affordable Accuracy 5000d as standaro 100% stainless steel construction Unlike other canister loadcells on the market today, all T302X loadcells will be supplied as standard with pre-greased top and bottom load buttons. This helps protect the load cell from harsh environments and helps to reduce load cell rotation. Custom designed to obtain the optimum electrical balance properties required for high accuracy weighing applications in industrial environments. Backward comparable - Being smaller means the new T302X can be used to directly replace old T302 with the aid of a retrofit adaptor block to take up the gap between the base location and the bottom of the canister loadcell. 20 metre cable length standard The T302X is also fully compatible with the 8701 ATEX version available OIML R60 approved to 5000d and available in 22.5 tonne and 45 tonne capacities. Available capacities: 22.5 tonnes 45 tonnes Fitted with 20 metre 4 wire 7 x 0.12mm core cable that has an electrically, mechanically and chemically tough polyurethane sheathed cable for added protection.Explanation / Answer
(a)
Load Cell Transducer is used to convert force into measurable electrical output. The data sheet provided is a load cell of 45 tunn load capacity.
Characteristics :
i. Recommended Excitation Voltage is 10V - 12V (AC or DC).
ii. Max. Excitation Voltage is 20V (AC or DC).
iii. Max load capacity is 45 tonns
iv. Niminal Input Impedance of 560 - 620 ohms.
v. Nominal Output Impedance is 480 ohms.
vi. Rated output is 1.75mV/V.
vii. IP69 Rating.
(b)
(i) Temperature Effect on Rated Output = 0.0008%/0C
The minimum temperature is -100C
Therefore, Minimum Temperature Effect on Rated Output = 0.000080C.
(ii) The max. overload that the load cell is able to measure without effecting its performance
= 150% of rated capacity
=150% 0f 45000kg
= 67.5 Tonnes.
(iii) IP rating means Ingress Protection Rating. According to International Standard, it classifies the degrees of protection provided against the introduction of solid objects.
Commonly IP is followed by 2 digits. First digit is for Solids Protection( Introduction of Solid Objects) and the second digit is for Liquids Protection ( Protection of the equipment inside the enclosure against harmfull ingress of water). In IP68, 6 is for solids protection and 8 is for liquids protection.
IP68 - Protected from total Dust Ingress(first digit) and Protected from long term immersion upto a specified pressure(Second Digit).
(iv) As it is a load cell transducer to measure a weight of a truck, the input of Wheatstone bridge is Force and the Output is Electrical Measurement of Weight.
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