The Simple Life

Sept. 20, 2004

PDAs have been around for a few years now and have evolved to the point that many are even more powerful than the top of the line laptop computers made available to the water and wastewater industry the past few years.

Generally, most PDAs have expandable memory to 1 GB, up to 400 MHz microprocessors and touch-screen displays and additional options that can include Querty keypad, wireless Bluetooth and cellular communication and GPS.

PDAs have been around for a few years now and have evolved to the point that many are even more powerful than the top of the line laptop computers made available to the water and wastewater industry the past few years.

Generally, most PDAs have expandable memory to 1 GB, up to 400 MHz microprocessors and touch-screen displays and additional options that can include Querty keypad, wireless Bluetooth and cellular communication and GPS.

Eventually, these relatively inexpensive devices will get into the hands of a good majority of water and wastewater maintenance personnel and become part of the standard assortment of maintenance equipment.

In the water and wastewater industry, instruments such as dataloggers and flowmeters use terminals or computers to display information. Most PDAs can be connected to these instruments through serial cables that can be used as a terminal but information is mainly limited to setting parameters, data downloading and very basic displays.

This exclusive story to WWD explains how PDAs can be useful for a growing number of unique and evolving applications within the water or wastewater industry.

Bad relays

In the water and wastewater industry, intermittent electrical problems are very common.

For example, Isco’s pump station monitor model 4501 records very accurate pump starts and stops. But even with an excellent performance record, intermittent chattering relays and alternators have been recorded in over 25% of the lift stations where this particular piece of equipment has been installed.

Many technical experts in the industry know that incorporating good dataloggers and analyzing software may be the only way to catch these intermittent conditions before they become emergencies or, at the very least, problematic.

As a result, new PDA-based monitoring systems, that not only address wastewater pump stations but everything that has a motor, are becoming increasingly popular with water and wastewater maintenance professionals.

Solving the problem

Under standard conditions, the electrical current used by water and wastewater-related instruments is a reflection of its condition. Industrial electricians know how important it is to monitor the current drawn from each phase of a motor from time to time and compare them between each other, as well as to previous historical data.

Problems reside in the fact that most maintenance personnel may not have the right equipment to do a specific job or they may not have the required training.

To do a job properly, maintenance personnel are beginning to rely upon smarter tools that compensate for a lack of specific specialized knowledge. If the missing knowledge is incorporated with better data recording and troubleshooting tools, then maintenance professionals may spend less time doing emergency repairs and more time conducting preventive maintenance. Most everyone in the water and wastewater industry knows how preventive maintenance can save a tremendous amount of money every year and it could very well be the next step in saving a utility even more money.

But problems can exist within a preventive maintenance program when specialized equipment must be installed and used by highly trained personnel.

However, it is possible to implement preventive maintenance without busting the operation budget by incorporating the use of a PDA-based maintenance system.

Because a PDA is able to download data from the datalogging equipment, maintenance personnel can analyze the information and correct problems on site.

Based on 17 years of experience in the development of pumping station monitoring systems and analyzing software, MAID Labs created a PDA-based software system called Motor Event and Current Recorder, or MerMaid. This software system offers a datalogger that can log 500,000 readings, one to nine current/ frequency clamps as well as PDA and Windows’ software.

This datalogger offers nine current transformer inputs for three motors or six current transformer inputs and three voltage inputs for two motors. Electric frequency is not important unless users are faced with a variable speed motor. In this case, the first input of a motor monitors current as well as frequency. In order to detect problems within a variable speed motor, both current and frequency are required.

Either every two seconds or when an event occurs, the unit’s microprocessor wakes up, reads all the current transformers and frequency, and if they have changed, they are recorded within an internal 2 MB flash memory. A 4-20 mA / 0-5V analog input is monitored and recorded the same way.

Downloading information to a PDA can done through an infrared port on the datalogger or with a remote infrared apparatus installed on the front of the electric control panel. This module can be magnetically attached, which is practical for temporary installations or attached to the panel.

Downloading is not mandatory to monitor the equipment connected to the datalogger because real-time display on the PDA is also possible.

Real-time screens graphically display the current drawn by each phase of each pump for up to three pumps at the same time making it is easier to detect unbalanced phases. On the same screen, users can view the minimum or maximum peaks or the frequency. The input display shows the value of the analog inputs, in addition to all of the digital inputs.

An Event Report presents each start and stop of the motor connected to the current transformer on the logger. An anomaly search button allows the user to go directly where the software has discovered potential problems like multiple starts and stops within a second or switching between motors several times per second. These two symptoms usually occur intermittently at first but could lead to contact fusion within the defective relay or alternator, which would ultimately burn the motor.

Concurrently, a Chart Report indicates some of the same information. Contrary to the Event Report, which represents one line per entry, the Chart Report is proportional to time and zoom functions to allow the user to see in detail the operation of its equipment.

Data is automatically added to the existing file for historical comparisons. Unless specified, only the newest data will be downloaded in order to minimize downloading time. It is possible to specify the quantity of events to download, but 500,000 readings of data can be a lot. Of course, the same PDA can download data for multiple dataloggers into separate respective files with the only limitation being the memory of the PDA.

Back at the office, the user can install his PDA on the cradle and press the synchronize button. All downloaded files are automatically transferred to the Windows software. When an installation file is opened, the software automatically appends the new data to the existing one.

Recent upgrades

This summer, MAID Labs incorporated the Volucalc extension of the MerMaid system, which is specialized for wastewater pump station applications. Volucalc and Isco’s Pumplink can measure volumetric flow meters with accuracy exceeding 98% for most constant speed pump stations.

“We have about 400 electric motors in one plant alone,” said Pierre Hardy, an electrician from Velan Valve Corp. who is currently using the MerMaid System. “Some of them break every couple of weeks without any apparent reason. I like the simplicity of use and installation of the MerMaid data because it monitors every electric parameters that I need to do some serious troubleshooting and proactive maintenance.”

Hardy went on to say, “Sometimes an oscilloscope with powerful data logging capacity would have been required to find some intermittent electric problems because our regular electric multimeters are not fast enough to show them. The software automatically searches for anomalies and also provides screens to compare recent current data with data logged a while back. It is like seeing a motor growing older. Most mechanical problems can also be detected this way because they change the current consumption of a motor.”

About The Author: Ben Beaudoin is executive vice president and general manager of MAID Labs Inc. He can be reached at 450/297-1115 or by e-mail at [email protected].

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