2 Wire, 3 Wire, and 4 Wire RTD Sensor Connections

Industrial temperature
transmitters (courtesy of
Siemens)

Industrial temperature transmitters are devices that measure the temperature of a process and provide a measurable output over some desired temperature range. Industrial temperature transmitters primarily use either of two popular temperature sensors - the thermocouple or the RTD (resistance temperature detector). The RTD changes resistance as process temperature changes, while a thermocouple provides a changing micro-voltage with process temperature change. RTDs are inherently more accurate, but require excitation voltage. There are three style RTD's - 2-wire, 3-wire, and 4-wire.

Proper connections for all three types of RTD sensor to a user- configurable transmitter are shown in the following illustrations:

Proper wiring of RTDs

It is critically important to note that the common connections shown by the symbols for 3- and 4-wire RTD sensors represent junction points at the sensor; not terminals jumpered by the technician at the time of installation, and not internal jumpers inside the transmitter. The whole purpose of having 3-wire and 4-wire RTD circuits is to eliminate errors due to voltage drop along the current-carrying wires, and this can only be realized if the “sensing” wire(s) extend out to the RTD itself and connect there. If the transmitter’s sensing terminal(s) are only jumpered to a current- carrying terminal, the transmitter will sense voltage dropped by the RTD plus voltage dropped by the current-carrying wire(s), leading to falsely high temperature indications.

Click here for more information on industrial RTDs and temperature transmitters.

For more information about any temperature measuring application, contact:
Ives Equipment
www.ivesequipment.com
(877) 768-1600

Some of above content taken from Lessons In Industrial Instrumentation by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.

Combustion Analyzer Adds Higher Level of Safety by Measuring O2, Combustibles, and Methane

The reliable identification of low combustion oxygen in a fired heater or boiler has always been critical to the effectiveness of the Burner Management System for proper control and safety.

Low emission burners and aggressive firing control points to achieve increased efficiency and emission reductions have driven the industry to tighter control measures. But tighter control measures also hold a greater potential for combustion events. Reducing the risk of a combustion event has become a priority and has led to the implementation of Safety Instrumented Systems (SIS). This additional layer of safety is added to the Basic Process Control System.

The WDG-V has been designed to provide an additional layer of safety with the measurement of excess O2, Combustibles and Methane and by using these measurements to ensure the safe operation of the Burner Management System.

WDG analyzers are based on a zirconium oxide cell that provides a reliable and cost-effective solution for measuring excess oxygen in flue gas as well as CO and methane levels. Information from the Gas Analyzer allows operators to obtain the highest fuel efficiency, while lowering emissions for NOx, CO and CO2. The zirconium oxide cell responds to the difference between the concentration of oxygen in the flue gas versus an air reference. To assure complete combustion, the flue gas should contain several percent oxygen. The optimum excess oxygen concentration is dependent on the fuel type (natural gas, hydrocarbon liquids and coal).

WDG-V Thermox Combustion Analyzer from Ives Equipment

Solenoid Valve Operating Principle

Solenoid magnetic field

A solenoid is an electric output device that converts electrical energy into a linear mechanical force.

At its most basic level a solenoid is an electromagnetic coil that uses magnetism produced by the flow of current to physically move the armature of a solenoid. The armature that is movable can be a rod or a metallic arm. One of the most common uses of solenoids are as the operators of valves.

A plunger solenoid contains a movable iron rod that is inserted into a coiled cylinder. The rod is connected to a plate with two contacts. With the aid of a spring the contacts are normally open. When an electrical current passes through the coil, it generates a magnetic field that attracts the rod into the coil chamber. The movement of rod will move the contacts into a closed position. When the current is turned off the magnetic force is removed and the tension in the spring forces the rod back out to its original resting position. This back-and-forth motion of the rod to control a circuit is used to operate a variety of mechanical devices such as valve seats and pneumatic poppets.

Solenoid valve components

A solenoid valve is a combination of two basic functional units:

• The solenoid (electromagnet) described above.
• A valve body containing one or more orifices.

ASCO Redhat Solenoid Valve

Flow through an orifice is controlled by the movement of the core when the solenoid is energized or de-energized. The core is enclosed in a sealed tube, providing a compact, leak tight assembly.

This video provides a very basic visual understanding of the solenoid operating principle and how the mechanism works. From this video it is easy to understand how the linear movement created by the solenoid can be transformed into the movement necessary to open and close solenoid valves.

For more information about solenoid valves, contact:

Ives Equipment

http://www.ivesequipment.com

877-768-1600

Lost Plant Air a Hidden Source for Energy Savings

Save energy costs by reducing
consumption of plant air.

Industrial plant air is one of the easiest sources of power to transmit and use. It’s also one of the most costly to generate. Information from the United States Department of Energy (DOE) indicates a wide variety of factors determine the cost of compressed air. These include, but are not limited to, local electrical energy cost, efficiencies of electric motors and compressors, load factors, and service time.

Plant maintenance are becoming more aware of air leaks and the subsequent increases in cost to overcome lost power because of those leaks. One of the major culprits for lost air in a plant is the pneumatic control valve positioner and the air required to operate them. In a typical process plant, there could be hundreds of control valves. Each control valve uses a positioner to move the valve actuator, based on a set point signal from a controller.

Control valve
with Siemens SIPART

It is the control valve positioner where the greatest air consumption savings lies.

Years ago, when electricity was cheap and when valve positioners were first introduced, plant maintenance and engineering were not concerned with something called the “bleed rate” of the positioner. Over the years though, plant personnel lost track of bleed rate and pretty much forgot that a positioner is just part of the system and it operates on air. Today, a modern process facility such as a power plant, refinery, or chemical plant can have several hundred control valves with positioners. The combined air loss due to the positioner “bleed rate” can be significant.

Siemens SIPART positioners

An immediate solution to this problem is to replace the control valve positioners with modern, energy-efficient, low-bleed models. One model, the Siemens SIPART PS2 has a proven track record of providing substantial savings to large plants. In one case, a tabacco company that had 2500 positioners was planning on spending $600,000 on a new compressor to increase output. After reviewing the capabilities of the low bleed positioner and running some tests, the plant decided to implement a plan for replacing the positioners which mitigated the need for a new compressor.

The significant change in technology came with the adoption of the adoption of a piezo ceramic valve block in low bleed positioners. Traditional positioners used an I/P and spool valve which both leaked air. Over time the leaks from these two parts is significant.

Could you and your plant be in the situation where lost energy efficiency through leaky positioners is costing big bucks? If you’re even the slightest bit concerned, call in an applications expert now for a system review.

Adhesives Manufacturer Saves Energy and Stays in Compliance with Flammability Anayzer

Flammability analyzer increases
safety while lowering energy cost.

A large manufacturer of adhesives needed to reduce energy costs in their plant. A large part of their energy cost was literally going out the window in the ventilation system and associated fuel costs. The heated air they produced for ventilation was expensive, yet is was necessary in order to comply with the NFPA's (National Fire Protection Association) standard of 25% LFL (lower explosive limit) on solvent vapor concentrations.

The 25% LFL applies to areas using just ventilation, but increases to 50% LFL if a continuous flammability analyzer is installed. If the manufacturer installed vapor analyzers, they could reduce the amount of energy on ventilation and fuel.

To meet the objective of lowering energy costs, the company installed PrevEx Flammability Analyzers, manufactured by Control Instrument Corporation, on each adhesive dryer. The PrevEx is a flammability analyzer for lower flammable limit monitoring (LFL/LEL) designed to provide fast response time (less than 1 second), capable of quickly changing gas concentrations, and with failsafe performance.

PrevEx flammability analyzers use a heated flame cell and an integrated controller that continuously measures total flammable vapor concentrations from 0 to 100% of the Lower Flammable Limit (LFL) range. To avoid condensation during sampling, the entire analyzer pneumatic assembly is heated.

A PrevEx analyzer was fitted on each printing press dryer to detect the possibility of solvent vapor accumulation. The PrevEx analyzers were chosen because of their "Universal Calibration" feature which prevents downtime due to re-calibration requirements.

By installing the flammability analyzers, the manufacturer was able to decrease ventilation and the associated energy costs while still staying in compliance with the NFPA code.

To understand more about flammability analyzers, look over the product document below:

Control Instruments PrevEx Flammability Analyzer Brochure from Ives Equipment

For more information on flammability analyzers, contact:
Ives Equipment
www.ivesequipment.com
877-768-1600

Clamp-on Flowmeter Locates Hard-to-Find Water Plant Leak

SITRANS FUP1010 clamp-on flowmeter

A rural water treatment plant in the Southwestern United States treats, stores, and distributes 325,00 gallons per day of water to the village it serves. The village consumes an average of 125,000 gallons a day and can store up to 1 million gallons.

The Problem

Unfortunately, the treatment plant was also losing 210,000 gallons a day due to an unknown leak.
Because of the leak, water storage was critically low at 100,000 gallons and the water service had to be temporarily shut off to half the village.

The village management hired a consultant company, at $1000.00 a day, to find the leak. The consultant worked for about a week without any luck.

The Solution

Read in the document below on how a Siemens SITRANS FUP1010 clamp-on flowmeter was used to find the leak.

Clamp-on Flowmeter Locates Hard-to-Find Water Plant Leak from Ives Equipment

PART 1: Setting Up and Operating the United Electric One Series Safety Transmitter

One Series Safety Transmitter

This is PART 1 in a series of training videos for the United Electric Controls One Series Safety Transmitter.

The One Series Safety Transmitter is a pressure or temperature monitoring transmitter switch that provides a NAMUR NE 43 standard 4-20 mA analog output. Its programmable high-capacity solid-state safety relay output enables the fastest emergency shutdowns.

The One Series Safety Transmitter is certified for use in SIL 2 functional safety applications (HFT = 0), and is capable of SIL 3 applications when augmented by redundancy and voting logic. Its simple design means fewer nuisance trips — for greater safety, productivity, and throughput.

The One Series Safety Transmitter was designed with features that simplify installation, improve productivity, and eliminate nuisance trips. “I Am Working” sensor diagnostics with redundant data processing detect open, shorted, and plugged sensing elements.

The transmitter’s analog output conforms to the NAMUR NE 43 standard and provides process variable (PV) and detected-fault information. Discrete outputs provide a fail-safe (open) emergency shutdown when a fault is detected. Set point and deadband (reset point) are 100% programmable.

The instrument is password protected to prevent unwanted parameter changes; eliminating the risk of tampering. In addition, LED backlighting enhances viewing of process variables, parameters, and status in dimly lit areas.

1. Fewer nuisance trips for greater productivity
2. More affordable than adapting a process transmitter for SIS
3. Internal relay for faster emergency shutdowns
4. Higher safe failure fraction simplifies SIL achievement

For more information, contact:

Ives Equipment

(877) 768-1600

www.ivesequipment.com