City Installs New Hosted-SCADA Service with PLC Control
The City of Northville is a community of about 7,000 people in suburban Detroit.
The City of Northville is a community of about 7,000 people in suburban Detroit. Similar to other suburbs in the area, Northville buys all of its fresh water from the City of Detroit. Steve Heidt, Assistant Director of Public Works, recently initiated major improvements to the control and monitoring of the system.
The new system allows Northville staff to evaluate alarms and avoid responding to nuisance alarms.
The water system consists of a valve regulating flow from Detroit into a reservoir tank. Booster pumps then pump from the reservoir to an elevated tank, which then feeds the distribution system. The system had been controlled by a Healy-Ruff float-and-relay based system that was installed in the 1970s.
“We needed to do something to address the rate increases we were paying for our water. The original system was still working reliably, but we knew that upgrading to current control technologies could provide a lot of financial and operation benefits,” Heidt said.
The engineering firm of Orchard, Hiltz & McCliment (OHM), local rep firm HESCO and Healy-Ruff worked together to design and deliver a new control solution. The team selected the Healy-Ruff H2Ovation system, a Internet-based hosted-SCADA and remote access system.
The system seamlessly integrates true local PLC control and SCADA functionality with secure remote access. However, rather than the huge capital and engineering investments typically associated with SCADA, all the functionality is provided to Northville for a monthly service fee. H2Ovation also manages and maintains all of the technologies (communications, hardware, software) for the system.
The new system allows for much better control through modulating the supply valve and better management of scheduling and set-points.
“A system of our size would have never considered ‘buying’ such a full-blown SCADA system not to mention dealing with the hassles of owning and maintaining it,” Heidt said. “H2Ovation provides all of the benefits for a monthly service fee.
“I can now access anything I need to know about my system from anywhere. I can see my tank levels, pump status, change set-points and turn equipment on. I receive and acknowledge alarms. I can do all of this from my office, from home, or once even on a trip to Florida.”
Northville’s water rates from the City of Detroit are set based on peak hour/peak day usage. The original float-based control system would open the valve to bring in water to the reservoir tank – often at the most expensive times. Recent years saw rate increases as high as 26 percent.
OHM and HESCO helped implement a new system strategy based on the Healy-Ruff VPAC controller. The new system allows for much better control through modulating the supply valve and better management of scheduling and set-points.
“We went from significant double-digit annual increase to a reduction of over 10% in our rates from the City of Detroit,” Heidt said. “The investment in the control system upgrade has already paid for itself.”
The original control system also had a traditional “alarm dialer.” A generic “system pump failure” alarm would be sent to the Police Department, which would then contact the Department of Public Works. They would respond to 90 to 100 calls per year from the system – 75% to 90% of which were nuisance or minor alarms that did not require immediate attention or action.
“The system is more reliable and generates a lot fewer ‘nuisance’ alarms. Also, because we can access the system remotely, we can evaluate the problems rather than needing to send someone every time to check things out,” Heidt said. “I’ve only had to send people out to respond to actual events, like to run a generator during an actual power failure.”
When considering wages, overtime, mileage and other cost factors, eliminating 75-90 trips is now saving Northville more than $10,000 annually.
Of course, most problems seem to occur at the most inconvenient times. One important alarm event occurred in the early morning hours on the coldest day of the winter.
The Internet-based system integrates true local PLC control and SCADA functionality with secure remote access.
“I received a ‘high level’ alarm from the elevated tank before sunrise,” Heidt said. “I logged into the system at home and saw a huge spike in the level reading. I knew this was not possible and started to diagnose the problem. I suspected a problem with the level transducer. I was confident, based on the information from the system, that we were not overflowing the tower nor in any immediate danger of reaching any low-level condition. However, if needed, I could have turned a pump on (or off) from home.
“We had had that tower painted last summer and I had always wondered whether or not the painters had disconnected the heat tape on the transducer. I called one of our field techs and told him to stop at the store on the way into work and pick up some heat tape, then go to the tank site and install it. We had the problem fixed in one trip and before we even reached the low level set-point to start the pumps.”
Improved Data Integrity
The new system provides greater collection and retention of process and equipment data. This includes tank levels, system flows and pressures and pump starts and run-times. This information can help validate billing, fine tune system operation and highlight maintenance needs.
“We have used the data to ensure the accuracy of our usage from our supplier and adjust some of our operating and alarm set-points,” Heidt said. “We can also archive the information and retrieve any history we may need. We have also identified that one of our pumps is running much longer than the other, suggesting we have a proactive maintenance opportunity.”
Peace of Mind
Perhaps even bigger than the financial and operational improvement the H2Ovation solution has provided is the confidence and peace of mind it has given the Department of Public Works.
“I no longer come in on the weekend just to see if the system is running and I can go for days at a time without visiting the site. I know that if there is a problem, I will be notified and will likely be able to solve it remotely,” said Heidt. “This takes a lot of stress and headaches away from managing the system. It works fantastic and definitely makes my job easier!”