So you’ve decided you need a torque transducer? Now comes the fun part – choosing the right one. This presentation points out some factors to consider when making a selection.
Measurement of speed:
Mechanical Tachometers
Electrical Tachometers
Stroboscope
Non contact type of Tachometers.
Stress & strain Measurements:
Various types- Electrical Strain Gauge.
Gauge factor
Method of usage of resistance strain gauge for bending compressive & Tensile strains
Usage for Measuring torque.
Strain gauge Rosettes.
It is ppt on Forced sensor which describes the introduction to sensor and few definition of forced sensor. Then it explains the construction and how it is used. And in the end it explains the few application of Forced sensor in world.
This is a force sensitive resistor with a round, 0.5" diameter, sensing area. This FSR will vary its resistance depending on how much pressure is being applied to the sensing area. The harder the force, the lower the resistance. When no pressure is being applied to the FSR its resistance will be larger than 1M. This FSR can sense applied force anywhere in the range of 100g-10kg.
ELECTRICAL MEASUREMENT & MEASURING INSTRUMENTS [Emmi- (NEE-302) -unit-1]Md Irshad Ahmad
(1) Philosophy of Measurement-Methods of measurement, Measurement system
, Classification of instrument systems, Characteristics of instruments & measurement
systems, Errors in measurement & its analysis, Standards.
(2)Analog Measurement of Electrical Quantities-Electrodynamic, Thermocouple,
Electrostatic & Rectifier type ammeters & voltmeters, Electrodynamic wattmeter, Three
Phase wattmeter, Power in three phase systems, Errors & remedies in wattmeter and energy
meter.
This presentation gives the information about Force, Pressure and Torque measurements of the subject: Mechanical measurement and Metrology (10ME32/42) of VTU Syllabus covering unit-6.
Measurement of speed:
Mechanical Tachometers
Electrical Tachometers
Stroboscope
Non contact type of Tachometers.
Stress & strain Measurements:
Various types- Electrical Strain Gauge.
Gauge factor
Method of usage of resistance strain gauge for bending compressive & Tensile strains
Usage for Measuring torque.
Strain gauge Rosettes.
It is ppt on Forced sensor which describes the introduction to sensor and few definition of forced sensor. Then it explains the construction and how it is used. And in the end it explains the few application of Forced sensor in world.
This is a force sensitive resistor with a round, 0.5" diameter, sensing area. This FSR will vary its resistance depending on how much pressure is being applied to the sensing area. The harder the force, the lower the resistance. When no pressure is being applied to the FSR its resistance will be larger than 1M. This FSR can sense applied force anywhere in the range of 100g-10kg.
ELECTRICAL MEASUREMENT & MEASURING INSTRUMENTS [Emmi- (NEE-302) -unit-1]Md Irshad Ahmad
(1) Philosophy of Measurement-Methods of measurement, Measurement system
, Classification of instrument systems, Characteristics of instruments & measurement
systems, Errors in measurement & its analysis, Standards.
(2)Analog Measurement of Electrical Quantities-Electrodynamic, Thermocouple,
Electrostatic & Rectifier type ammeters & voltmeters, Electrodynamic wattmeter, Three
Phase wattmeter, Power in three phase systems, Errors & remedies in wattmeter and energy
meter.
This presentation gives the information about Force, Pressure and Torque measurements of the subject: Mechanical measurement and Metrology (10ME32/42) of VTU Syllabus covering unit-6.
Measurement of force and torque and pressure standardsMech-4u
Measurement of Force and Torque and pressure Standards,
Measuring Methods,
study of different types of forces and torque Measuring systems.
Description and working Principle of different types of Transducers for Measuring Pressure.
Here my project theme is to monitor and control Transformer health using Arduino, as we all know there are both internal and external faults occur in the transformer, for internal faults we use Buchholz relay and Differential protection relay for external but it is not efficient with time. so,we use Arduino for real time protection, here we fix some values to the Arduino in the program itself according to the rating of the transformer by that we monitor and control whenever the faults occur
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
call for paper 2012, hard copy of journal, research paper publishing, where to publish research paper,
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals
This paper explores the fundamental characteristics of medium to high capacity load cells and how they are affected by the types and implementation of strain gages.
Load Cell Lunch and Learn Presented by InterfaceInterface
This in-depth presentation is a detailed crash course on load cells and force measurement for a wide variety of applications. Learn more about our history, unparalleled track record and our products.
Interface is the World Leader in High Accuracy Load Cells for Force Measurement. This presentation covers why our load cells and torque transducers are the best in the business and set the bar higher for our competitors.
Interface has offered sensors with various types of SELF-ID for many years. The SELF-ID features
eliminates the need to enter data via a keyboard or key panel from a paper calibration sheet into the
instrument used with the load cell.
This presentation, developed in 2005 is one of our most popular.
Shunt Calibration is a technique for simulating strain in a piezo-resistive strain gage Wheatstone bridge circuit by shunting one leg of the bridge. The bridge may be internal to a discreet transducer or composed of separately applied strain gages. The resulting bridge output is useful for calibrating or scaling instrumentation. Such instrumentation includes digital indicators, amplifiers, signal conditioners, A/D converters, PLC’s, and data acquisition equipment.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
"Impact of front-end architecture on development cost", Viktor TurskyiFwdays
I have heard many times that architecture is not important for the front-end. Also, many times I have seen how developers implement features on the front-end just following the standard rules for a framework and think that this is enough to successfully launch the project, and then the project fails. How to prevent this and what approach to choose? I have launched dozens of complex projects and during the talk we will analyze which approaches have worked for me and which have not.
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
Neuro-symbolic is not enough, we need neuro-*semantic*Frank van Harmelen
Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as “predictable inference”.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
2. Interface Inc. • 7401 East Butherus Drive • Scottsdale, Arizona 85260 USA • Phone: 480.948.5555 • Fax: 480.948.1924
www.interfaceforce.com • Email: contact@interfaceforce.com • ORDER TOLL-FREE 800.947.5598
2
So you’ve decided you need a torque transducer? Now comes the fun part – choosing the
right one. The following pages will point out some factors to consider when making a
selection.
There are two basic types of torque transducers; rotary and reaction.
A reaction or static torque transducer measures torque without rotating, while a rotary torque
transducer rotates as part of the system. A rotary sensor is merely a reaction sensor that is
allowed to rotate. Normally, a reaction style sensor has a cable attached to it for supplying
excitation voltage to the strain gage bridge and for output of the mV/V signal. Spinning of
these sensors is prevented by the attached cable. To get around the issue of the attached
cable, a variety of methods have been used for rotary sensors. Some of those methods
include slip rings, rotary transformers, rotating electronics, rotating digital electronics and
radio telemetry.
A torque transducer, like a load cell, consists of a metal spring element, or flexure. Strain
gages are applied to the flexure in a Wheatstone bridge configuration. Torque applied to the
sensor causes bending or shear strain in the gaged area, generating an output voltage signal
proportional to torque.
Slip rings are among the original methods used for power and signal transfer. The rotating
sensor has a set of metal rings pressed onto its shaft. Each corner of the strain gage bridge
is connected to a ring. Carbon silver brushes slide on the rings, transferring power and
signal. Slip ring sensors are usually not recommended for continuous or high-rpm use
because of wear in the brushes, which causes dust, creating noise in the signal. Slip-ring
sensors require periodic cleaning and brush replacement . An advantage of slip-ring style
sensors is they can be used with traditional mV/V instrumentation.
Another commonly used method involves rotary transformers. This method uses a set of
transformers, one to carry the excitation voltage onto the shaft, and the other to transfer the
signal off. They are called rotary transformers because one winding of each transformer
rotates relative to the other winding. Advantages of this approach include low noise and no
wearing parts in the electrical path. Because of the AC nature of transformers, AC carrier
amplifiers are required for the signal conditioning. Some rotary transformer torque
transducers include built-in signal conditioning, allowing for a standard DC supply voltage
and a high-level signal output.
The next type of rotary torque transducer adds electronics to the rotating shaft. Unlike rotary
transformer sensors, these types actually have strain gage amplifiers and signal converters
directly on the rotating shaft. Power is still transferred inductively, but unlike rotary
transformer sensors, shaft electronics condition and rectify the supply voltage, amplify the
bridge output signal, and convert the signal for inductive transfer back to the stator. In a
simple case, the signal is converted and transferred as a frequency and then converted from
frequency to DC voltage output in the stator electronics. An advantage of this approach is
lower manufacturing cost, since precisely wound and aligned transformers are not required.
A more complex approach involves digitization of the torque signal on the rotor. This
approach adds an A/D converter, digital signal transfer across the inductive coupling, and
D/A conversion in the stator. Advantages of this approach include the ability to switch a
shunt resistor directly at the strain gage bridge.
When choosing a torque transducer, one of the primary considerations is selecting the right
capacity. On one hand, if you choose too large a range, the accuracy and resolution may not
be enough for the application. On the other hand, if you choose too small a size, the sensor
may be damaged due to overload, which is an expensive mistake. No manufacturer wants
you to overload the sensor, even if it results in the sale of a replacement part. We’d much
rather have happy customers with functioning systems. In the end, the customer takes final
responsibility for choosing the proper size for his application.
continued...
3. Interface Inc. • 7401 East Butherus Drive • Scottsdale, Arizona 85260 USA • Phone: 480.948.5555 • Fax: 480.948.1924
www.interfaceforce.com • Email: contact@interfaceforce.com • ORDER TOLL-FREE 800.947.5598
3
To select the proper size, first determine the amount of torque you want to measure. This can
be easy or hard, depending on your application. An easy example would be a fastener
torque application, where a certain amount of torque is to be applied to a fastener. A more
difficult application might be trying to figure out how much torque is required for a new design
wind turbine
If there’s a motor involved, you can usually read the rated hp and rpm off the nameplate.
Once you know that, average running torque can be calculated from one of the following
equations:
Torque in lb-ft = (Horsepower x 5,252) / RPM
Torque in lb-in = (Horsepower x 63,024) / RPM
Torque in Nm = (Horsepower x 7,121) / RPM
After you determine the maximum average running torque of the system, the next step is to
decide how much safety-factor you need to prevent overloading the sensor. In rotary torque,
there is always one side of the sensor being driven, and the other side being loaded. Some
drives and loads stress the torque transducer more than others. These drive and load factors
must be taken into account when determining the maximum peak torque in the system.
Load Service Factors from 1 to 4 can be assigned to different types of loads, with 1 being the
least severe. Examples of service factor 1 devices are smooth running, constant rpm items
such as fans and centrifugal blowers. Liquid pumps and axial compressors also fall into this
category.
Going up the scale, load service factor 2 devices are non-reversing, non-constant load or
start/stop devices. Examples include briquetter machines, cranes and hoists, conveyors,
extruders and mixers.
Load service factor 3 devices involve high variable shock or light reversing loads. Examples
include crushers, single-cylinder reciprocating pumps, vehicle drivelines and hammer mills.
Level 4 devices are the most severe and involve heavy to full torque reversals including
reciprocating compressors.
Next you must consider drive service factors. Much the same as loads, different types of
drives offer different levels of severity, influencing the maximum expected peak torque in an
application. Drive service factor 0 devices are the easiest and include turbines or smooth
running DC or 3-phase AC motors. Factor 0.5 devices include 8-cylinder gas or 10-cylinder
diesel engines and single-phase AC motors. Moving up the scale, drive service factor 1
devices include 6-cylinder gas or 8-cylinder diesel engines, and 3-phase AC motors
controlled by variable frequency drives. Examples of drive service factor 1.5 devices include
4-cylinder gas or 6-cylinder diesel and single-phase VFD controlled AC motors. Topping out
the range with drive service factors from 2 to 4 include less than 4-cylinder gas and less than
6-cylinder diesel engines. Diesel engines have high compression ratios and cause torque
peaks that can be 4x or 6x the average running torque, leading to rapid use of the fatigue life
and premature transducer failure.
Finally, one must consider startup conditions. When starting a high inertia load with an
electric motor, very high peak torque can result. One thing to check is the starting torque
rating of the motor, if you can find it. Diesel engines can also have very high starting and
stopping torques of 6x running torque.
Maximum expected peak torque can be calculated by taking the above factors into
consideration. Peak torque is equal to average running torque x (load service factor + drive
service factor). This is the recommended capacity of your torque transducer.
continued...
4. Interface Inc. • 7401 East Butherus Drive • Scottsdale, Arizona 85260 USA • Phone: 480.948.5555 • Fax: 480.948.1924
www.interfaceforce.com • Email: contact@interfaceforce.com • ORDER TOLL-FREE 800.947.5598
4
For example, consider a briquetting machine being driven by a VFD controlled 3-phase AC
motor. The motor is rated for 150 hp at 1790 rpm. From the equation above, calculated
average running torque in Nm is (7121 * 150) / 1790 = 597 Nm. A briquetting machine has
load service factor 2 and the VFD controlled 3-phase AC motor has drive service factor 1.
Adding these together we get combined service factor 3. We then multiply 3 * 597 Nm to get
1790 Nm as the expected peak torque. In this case a torque transducer of at least 1790 Nm
capacity would be selected.
Once the required capacity has been determined, it’s important to consider the accuracy and
resolution of the measurement. Torque transducer accuracies are usually quoted as a
percentage of capacity. A common rating is 0.1% combined error. For example, 1000Nm
sensor, when used anywhere within it’s 1000Nm rating, will have nonlinearity and hysteresis
error of no more than +/-0.1% of 1000Nm, or +/-1Nm. When measuring an average running
torque of 800Nm with this sensor, the +/-1Nm may be just fine. However, if the application
has a very low ratio of average running torque to maximum peak torque, it may be necessary
to use this same transducer to measure a running torque of 100Nm. In this case, +/-1Nm out
of 100Nm is a 1% error. Choosing a transducer with enough capacity to survive the
application can make it difficult to achieve high accuracy. As always, compromises must be
made.
Another way to allow for high overloads while still accurately measuring smaller torque values
is to use a multi-range sensor. For example, if you have a system with high load and service
factors you might have a relatively low running torque but high peak values. If you want to
accurately measure both the running and the peak torques then a dual-range sensor would
be a good choice. Ratios of high to low capacity on dual range torque transducers are
typically 5:1 or 10:1. The safe overload rating of the sensor is equal to 2x the higher range.
Some newer sensors, such as the Interface model HRDT, allow for adjustable scaling of the
output, and multiple outputs from a single sensor. For example, a 1000Nm sensor could be
scaled for +/-10V output over +/-300Nm.
Another factor to consider is resolution of the measurement signal. Analog sensors such as
slip-ring or rotary transformer types have essentially infinite resolution, limited by the signal to
noise ratio of the system. On the other hand, digital rotary torque transducers are subject to
the bit resolution of their analog to digital converters. Typical digital sensors are 12 or 16-bit
or higher. A 12-bit sensor has 4096 counts over its -Full Scale to +Full Scale range. What
this means is the resolution over one direction of the measuring range (CW or CCW), is 2048
counts. For a 1000Nm 12-bit sensor, resolution is therefore about 0.5Nm. If that’s not
sufficient, a higher resolution sensor should be selected. In contrast, a 16-bit 1000Nm
sensor will have 0.03Nm and an 18-bit 1000Nm sensor has 0.008Nm resolution.
Torque transducers typically come in one of two major mechanical configurations, shaft or
flange style. Shafts can be either smooth or keyed with keyed shafts coming in either single
or double-keyed versions. Flange style sensors are typically shorter than shaft style, and
have pilots on their flange faces as a centering feature.
Smooth shafts offer some advantages over their keyed counterparts, including more uniform
introduction of the torque into the measuring shaft, ease of assembly and disassembly and
zero backlash. A coupling designed for use with smooth shafts will have some method of
clamping to the shaft. This is commonly accomplished with split collars or shrink-disk style
hubs. Shrink-disk style hubs usually include features to aid in their removal from the shaft.
Hubs for keyed shafts are simpler than those for smooth shafts and cost less but can suffer
from wear due to backlash, especially in reciprocating applications. To prevent backlash, the
hub must be installed on the keyed shaft with an interference fit, which is usually
accomplished by either heating the hub before installation or pressing the hub onto the shaft.
continued...
5. Interface Inc. • 7401 East Butherus Drive • Scottsdale, Arizona 85260 USA • Phone: 480.948.5555 • Fax: 480.948.1924
www.interfaceforce.com • Email: contact@interfaceforce.com • ORDER TOLL-FREE 800.947.5598
5
Pressing of the hub risks damaging the sensor and both installation methods present
problems with removal. Another less common method of installation and removal uses
special hydraulic equipment. In the higher torque capacities double keyways are often used,
spaced at 180 degrees around the shaft.
The two main categories of coupling are single and double-flex, also referred to as half and
full couplings. A single-flex coupling has flex point, and allows only angular misalignment.
Radial misalignment, perpendicular to the axis of rotation, is not possible. A double-flex has
two flex points and allows both angular and radial misalignment.
Some available styles of coupling are Flexible Disk, EDM cut, Precision Gear, U-joint and
Elastomer. Of these styles, Flexible Disk couplings are desirable for torque measurement
because of their high torsional rigidity and zero backlash. Torsional rigidity allows for fast
dynamic response and low ‘wind-up”. A less rigid coupling will mechanically dampen the
signal, possibly reducing or eliminating the ability to measure transient events. Another
desirable quality of flexible disk couplings is they can be balanced for high RPM operation.
Rotary torque transducers come either supported on bearing in a housing, or are
bearingless. Bearing supported designs maintain alignment between the rotating and
stationary parts of the sensor and can be easier to mount. Bearingless sensors require the
non-rotating part of the sensor to be held in a precisely fixed position relative to the rotating
part. Some bearingless sensors are more forgiving of alignment issues than others.
There are two main methods of mounting rotary torque transducers, fixed or floating. Fixed
mount applies only to sensors with bearings and involves attaching the sensor housing to a
fixed support.
continued...
Double-flex
couplings
Drive Load
Torque
Sensor
Figure 2. Fixed Mount
α angular
α
Single Flex
Double Flex
Radial = l tan α
l
Figure 1. Single and Double-Flex Couplings
Single Flex
Coupling
4/22/1
6. Interface Inc. • 7401 East Butherus Drive • Scottsdale, Arizona 85260 USA • Phone: 480.948.5555 • Fax: 480.948.1924
www.interfaceforce.com • Email: contact@interfaceforce.com • ORDER TOLL-FREE 800.947.5598
6
In floating installations the sensor is supported only by its drive and load side connections,
which are typically single-flex style couplings. A flexible strap keeps the torque transducer
housing from rotating. By definition, bearingless sensors are always floating mount.
Fixed mounting requires that the sensor housing have a means to attach it to the support.
Sometimes the mount is an option on the sensor and sometimes the foot or pedestal mount
is built as part of the sensor. The simplest fixed-mount design sensors include a flat
machined surface on the housing with threaded mounting holes. In fixed mount installations,
double flex couplings must be used.
Fixed mount can be better for high rpm use, limiting the lengths of the unsupported rotating
sections. Foot or pedestal mounted sensors are not designed to be used as bearing blocks,
so care must be taken to ensure against unduly loading the bearings. An example of a fixed
mount application is electric motor testing, where it’s important to quickly move motors in and
out of the test stand. By mounting the torque transducer and load to a fixed plate, the
alignment between the two can be set once and maintained indefinitely. The test motor can
then be coupled and uncoupled from the sensor with no worries about the sensor losing its
support each time the motor is disconnected. In contrast, if the sensor is float mounted, each
time the motor is disconnected the torque transducer must be supported from drooping.
Floating mounts are more forgiving of misalignment between the drive and load. A floating
sensor, mounted between two single-flex couplings, is essentially a long double-flex
coupling. Since the allowable radial misalignment is directly proportional to the distance
between flex points, the floating mount installation is more tolerant of misalignment between
the drive and load.
Another advantage of floating mounts is the reduction of the effect of extraneous loads on the
sensor. For example, in a floating mount system, a thrust load is carried only by the sensing
element with no effect on the bearings. In a fixed mount installation, any thrust load becomes
a load on the bearings, causing premature wear in the bearing and possibly contact between
the rotating and stationary parts if the shaft shifts within the housing. The thrust load rating of
a floating mount sensor is typically orders of magnitude greater than a fixed mount.
As with any sensor, environmental factors must be considered. Some things to consider are
temperature and exposure to moisture or dust. For temperature, rotating torque transducers
usually have a storage range, an operating range and a rated or compensated range. The
storage range is the temperature over which the sensor can be stored without damage. While
it won’t hurt the sensor to store it within this range, it must be used within its operating range
or it might be damaged. The compensated or rated range is the temperature over which the
torque transducer is guaranteed to meet its published temperature specifications. Depending
on the sensor, the temperature performance will be two or more times worse when outside
the rated range. If the sensor must be exposed to temperature extremes then steps should
be taken to shield or protect it. Heating blankets or enclosures are sometimes used.
continued...
Single-flex
couplings
Drive Load
Flexible Strap
Figure 3. Floating Mount
Torque
Sensor
7. Interface Inc. • 7401 East Butherus Drive • Scottsdale, Arizona 85260 USA • Phone: 480.948.5555 • Fax: 480.948.1924
www.interfaceforce.com • Email: contact@interfaceforce.com • ORDER TOLL-FREE 800.947.5598
7
Another environmental factor to consider is electrical noise. Some installations are noisier
than others, especially where electric motors and/or variable- frequency drives are employed.
Variable-frequency drives (VFD) are used to control the speed of an AC electric motor by
controlling the frequency of the electrical power supplied to the motor. Other names for VFD
are adjustable-speed drives (AFD), AC drives, inverter drives or variable-speed drives (VSD).
When a torque transducer is used in conjunction with a VFD, proper grounding and shielding
techniques must be used to prevent torque transducer malfunction. During operation, a VFD
creates noise on the power line and radiates noise from the VFD-to-motor cable. Noise is
also capacitively coupled from the motor windings into the motor shaft and through the
bearings into the motor frame, and from un-shielded motor leads in a conduit to the conduit
supports.
To ensure a successful installation, the VFD supplier grounding recommendations should be
followed, including use of a shielded motor feed cable.
In rotating torque measurement the sensor will be spinning, so it’s important to know what the
maximum RPM will be and to make sure the torque transducer can withstand it. Limiting
factors may be bearing life, rotating electronics or balancing, depending on the type of
sensor. You must also consider the limits of other parts in the rotating assembly such as
couplings. Typically, rotating parts will have a published rpm limit. Sometimes those limits
can be increased with special balancing or special component parts. If in doubt, please check
with the manufacturer.
Rotating torque measurement is rarely a steady value, more commonly varying around some
average value. In certain only the average torque is important, but in other cases the
transient torque peaks are of interest. In either case it’s important to understand the
sampling rate and/or measurement bandwidth of the system.
Rotating torque transducers should always list a measurement bandwidth and/or a sampling
rate on their data sheets. Depending on the type, bandwidth can range from a couple of
hundred Hz to several thousand or more. An application where average running torque is
typically measured is engine dynamometers. In this case you may not care about torque
spikes caused by individually firing cylinders so they can be filtered out, either by the sensor
or in the data acquisition electronics.
In other cases, the peaks and valleys of the torque signal are important, and a sensor with
enough bandwidth must be selected. For example, in an end of assembly line gearbox test it
may be important to check if one of the individual gear teeth is broken or if the gears aren’t
seated properly. This could be determined by comparing the torque signature of the tested
part to a known good one. In a 1:1 ratio right-angle gearbox with 60-tooth gears spinning at
500 rpm, a tooth engages 500 times per second. To accurately profile the tooth engagement
you would need a torque transducer with bandwidth of at least 500 Hz.
The proper selection of a torque transducer can be confusing, particularly if you have no
precedent to draw from. Therefore it is important to work with a reputable manufacturer and
knowledgeable sales person. In summary attention must be given to proper capacity, speed,
connection, mounting and environment.
By: Keith Skidmore
Torque Sales Manager, Interface Inc.
keiths@interfaceforce.com