INTERACTIVE DEMAND MANAGEMENT SYSTEM

Substantially reduces utility charges by driving down total KW demand of a group of electric melting furnaces without impairing production rates or casting quality

Introduction

Rayteq's new Fleet Commander™ Interactive Demand Management System (IDMS™) is new, next-generation technology that enhances the many benefits of electric resistance melting by dramatically reducing electric utility demand charges of a group or fleet of electric melting furnaces by interacting with and synchronizing each furnace's power demand.

All Rayteq electric furnaces include Furnace Director™' custom designed programmable logic controller (PLC) that operates the furnace, tracks critical production variables such as metal bath temperature and furnace power consumption, and networks with the central IDMS™ computer. This central computer, equipped with Rayteq's Fleet Commander™ software, can coordinate an unlimited number of electric furnaces equipped with Furnace Director™ PLCs to effectively hold total fleet kW demand to the minimum required to meet production melting needs without adversely impacting metalcasting performance.

Fleet Commander™ IDMS™ is several times more effective than first-generation open-loop, non-interactive demand management systems (DMS) yet it does not impair production rates or casting quality


IDMS™ System in Operation

    What does a digital IDMS™ production melting system look like? The adjacent photo shows a new, IDMS™-equipped Rayteq electric resistance melting furnace supplying molten metal for a typical die casting production cell. Even though it's very compact this furnace will melt 720 lbs./hr. of aluminum alloy.

Model DC - Melts 720 lbs/hr while operating as part of IDMS™ controlled fleet


Model DC-650 Control Panel

Rayteq Control Cabinets

    Photo to the left shows Rayteq's unique hybrid digital/analog control cabinet for the furnace above. It contains the required Furnace Director™ PLC which is connected via Ethernet cable or wi-fi bridge to Rayteq's central Fleet Commander™ IDMS™ computer that synchronizes and limits the KW demand for all the electric furnaces connected in this IDMS™ fleet.

    The parallel-wired heating elements in the above furnace are separately monitored and controlled. Tri-color LED element status lamps indicate element on (green), element off (amber), or element circuit fault (red). Each heating element has its own circuit breaker and the controls operate at 24 volts for safe troubleshooting.


Demand Management Theory

Electric utility monthly demand charges are determined by the highest (peak) average kW demand over a 15 to 30 minute period, typically during a calendar month, as recorded on the utility's demand meter. The theory behind both Rayteq's new IDMS™ and the more conventional DMS is that unsynchronized electrical equipment, including electric melting furnaces, will randomly but inevitably draw maximum power simultaneously a number of times during the utility's month-long demand metering cycle. Just one such incident will drive the utility demand charge up to the maximum possible cost for that month. Because most metalcasters do not operate their equipment including furnaces at maximum red-line output there will always be room to reduce the total fleet kW demand. Demand management systems work to reduce utility demand charges through synchronized restriction of the total kW demand of an electric equipment group, and the manner in which they accomplish this has a major impact on (a) demand reduction effectiveness and (b) production output and quality control.


How Rayteq IDMS™ Works

Rayteq's Fleet Commander™ IDMS™ custom programmed software is loaded into an industrial-grade computer that communicates with a fleet of electric resistance furnaces equipped with Rayteq's Furnace Director™ PLCs via standard Ethernet cables or industrial-grade wi-fi radio bridges. A furnace participant may be a Rayteq designed and built furnace or it can be a compatible conventional furnace such as a Dynarad* or StrikoDynarad* electric melter equipped with the Rayteq IDMS™ retrofit control panel which contains the required Furnace Director™ PLC.

Regardless of fleet makeup, the IDMS™ mission is interactive kW demand management to minimize the total kW electrical demand of the entire furnace fleet supplied from a single metered electrical service without compromising the user's production and quality control requirements.

In operation, the Rayteq IDMS™ software gathers all relevant information about the fleet and periodically provides each Furnace Director™ PLC with recommended actions which may include kW reductions in the form of heating element brownout for each furnace. Each Furnace Director™ PLC considers the impact of these recommendations on the user's preset production and quality control requirements before deciding to what extent it will implement them. In addition, the Furnace Director™ PLC can elect to shed a previously accepted brownout recommendation that is still in effect should it later become incompatible with the user's production requirements. Giving each Furnace Director™ PLC local decision-making authority ensures that the user's production and quality control needs for each furnace are always properly maintained.

Fleet Commander™ continuously tracks kW demand of all electric furnaces in its fleet, making it an effective sub-metering system. It is also a comprehensive data logger, storing nearly all of the information it gathers for later examination. Should strange things happen in the night they can be tracked down and examined at a later time, making Fleet Commander™ valuable as an analytical tool.


IDMS™ Retrofit Control Panel for Older Furnaces

    Other electric furnace makes can be modified to operate with Rayteq's Fleet Commander™ IDMS™ with the addition of a Rayteq IDMS™ retrofit control panel (see adjacent photo). Most electric resistance furnaces can be upgraded including Dynarad* and StrikoDynarad* and similar contactor operated electric melters as well as furnaces with proportional output solid state, SCR and thyristor controls.

    These retrofit control panels include the necessary Furnace Director™ PLC, tri-color LED element status lamps and test button, and an LED lamp that indicates when demand control is in effect. Thorough field tests confirm these IDMS™ retrofit control panels operate as effectively as the original Rayteq hybrid controls, but at a lower capital cost.

Retrofitted StrikoDynarad EC-2400 Control Panel


Comparing Rayteq IDMS™ with Conventional DMS

Fleet Commander's highly effective control method spreads a large demand reduction across the entire furnace fleet in an orderly and efficient manner instead of applying harsh rolling 100% blackouts to one or more furnaces, whether they are meeting production needs or not, as do conventional first-generation on/off, non-interactive demand management systems (DMS). Because these early systems have no awareness of the state of each furnace, they attempt to hold total plant demand to supervisor adjusted, arbitrary set-point limits with no special attention given to any individual furnaces which may be falling short of the user's required melting rates. In many cases this set-point limit is set unnecessarily high due to the supervisor's hesitancy, possibly because of previous bad experience with production disruptions, and setting a higher than needed maximum power limit results in lower cost savings. By contrast, Rayteq's interactive approach considers the conditions in each furnace before taking action, thus maximizing overall demand reduction while maintaining quality control and full production without interruption.

Every night after the last production shift the Fleet Commander™ IDMS™ automatically begins recalculating the furnace fleet's daily kW demand requirements based on adjustments to production rates as well as changes in furnace status (on-line, off-line, etc.) without requiring a supervisor to input any demand set-points or continually tweak the furnace fleet kW demand target. As a result, Rayteq's IDMS™ continuously adapts and squeezes every last drop of demand out of its furnace fleet without any human interaction or guesswork. The results are impressive - net IDMS™ kW demand savings can exceed conventional demand management systems by 100% to 500%!

Watching IDMS™ in Action

The above image shows an actual graphic, real-time daily readout of a four-furnace IDMS™ fleet during full production melting operations. The yellow line near the top represents the maximum possible peak demand of 414 kW, which is the combined kW ratings of all four furnace. The green trace shows what the total kW demand would have been without IDMS™ control (it would have reached maximum peak demand of 414 kW just after 6 AM and again at 2 PM), while the blue trace shows that the IDMS™ held the peak demand to 194 kW, a demand reduction of 53%. The red line shows the actual peak demand of 194 kW for the day, and the difference between the red and yellow lines is the actual IDMS™ controlled demand reduction of 220 kW for the day. Both real-time and historical demand control graphs and data can be viewed any time on an office-networked computer using any standard web browser.


Anticipating IDMS™ Results

How much of a reduction can be anticipated with IDMS™? While we've seen reductions between one-third to more than one-half of the total connected kW, the answer in any given case will depend on how many production cells are idle due to die or pattern changes, how many energy intense production jobs might be running simultaneously, etc. In a job shop where short and medium run jobs quickly move in and out of production, the results will be hard to predict. However, it is important to note that even in such circumstances, Rayteq's IDMS™ will restrict kW demand to just what is needed to meet actual production melting requirements. With Rayteq Fleet Commander™ IDMS™ now available, it should no longer be acceptable to allow uncontrolled, random kW demand peaks determine the metalcaster's monthly demand charge when IDMS™ is fully capable of reducing it.


Alert System

Fleet Commander™ IDMS™ includes the ability to sense multiple types of events at each furnace such as:

Email alerts for all of the above can be delivered automatically to the appropriate personnel allowing for immediate corrective action.


Summary

The introduction of Rayteq's Fleet Commander™ interactive demand management systems (IDMS™) for electric resistance melting furnaces has created a unique opportunity for metalcasters everywhere to reduce their aggregate kW demand, and hence the total electric utility expense, of electric resistance furnace fleets without impairing production rates or quality control, making them highly competitive with fuel fired melting. This means that even in states like California and the eastern seaboard where electricity is expensive, they can once again enjoy all the positive benefits of electric melting while substantially reducing their electric utility costs, truly giving them the best of both worlds.

*Dynarad and StrikoDynarad are trademarks owned by the Striko-Westofen-Dynarad Furnace Corporation (a.k.a. StrikoDynarad). Rayteq is not affiliated with StrikoDynarad.