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Dencor SERIES 300CEnergy Administration System Effective Energy Cost Control
A Dencor Series 300C Energy Administration System will SAVE YOUR BUSINESS MONEY. Your company now has a way to make electric rates WORK FOR YOU. Avoid high demand and energy charges. Use the Series 300C to decrease your peak electrical demand, reduce energy usage, and shift energy usage to off-peak times. The Series 300C is the most powerful Energy Administration System available for small businesses, office buildings, nursing homes and fast food outlets. The 300C includes special features to control demand for diesel generators. Dencor has built Energy Administration Systems since 1976. The Series 300C provides all the features found important in thousands of successful installations.
Monitor and Control a Building from a Remote Location System Description: The Series 300C controls major building loads for customers on Time-of-Use Demand, Full-Time Demand or Coincident Demand rates. The controller can monitor two system demands; a primary demand and an auxiliary demand. All loads can be influenced by either or both demands. The primary demand control system has a very versatile set of control strategies. The auxiliary demand system provides for priority shedding. The auxiliary system may be used to monitor a large load or for control of loads on a separate meter. Operates Under Windows 95: The system includes a 300C controller and PC software. The software provides:
Modem Communication: Communication between the PC and the 300C may be made using a modem or by direct connection to a PC serial port. The 300C operates independently of the PC and only needs a connection when data contained in the 300C is to be downloaded to the PC or when parameters in the 300C need to be changed. Analog Inputs: Four analog inputs are available. One may be used for current transformer measurement of demand if KYZ pulses are not used. Temperature sensors, 0-5 Volt, and 4-20 ma sensors may be used to generate signals to modify or limit shedding operations of loads. This may be used for freeze protection or over/under temperature limiting. Average or instantaneous demand may also be used in the same way as analog inputs to modify load control. Digital Inputs: Four digital inputs are
available. One or two may be used as KYZ demand monitoring inputs. Dry contact inputs may
be used for a variety of actions. These may include shifting the demand setting from
on-peak to off-peak, or shifting the demand setting level to a critical demand setting. A
dry contact may also be used to shift the primary demand control from one input signal to
another. This is important for demand control of a generator's load. Shorter averaging
intervals may be desired when using diesel generators. Five Primary Relay Control Modes: The primary demand control system permits each relay to be assigned to any one of five different primary modes of control. Each relay also has several secondary modes of control available for additional flexibility. The primary modes of control are: Standard Priority: The first shed is the last restored. There are 16 priority levels. Rotating Ring: Loads take turns being shed. A ring of eight addresses is assigned to eight priorities. If three of the associated priorities are shed then three in the ring will be shed. Loads in the ring will take turns being shed. Variable Duty Cycle: Loads take turns being on. Loads assigned to this ring of eight have a minimum on-time specified so they are on for at least the minimum time during each cycle. The load turn-on times are spread over the cycle. When a load is turned off it remains off until the turn-on time for that cycle. The ring of eight addresses is assigned to eight priorities and will have as many loads off as associated priorities are off unless the minimum on-time keeps more loads on. The variable duty cycle is used to keep loads off less than they may be with an equivalent rotating ring. Duty Cycle: Loads cycle on and off with a specified on-time and cycle time. Eight load turn-on times are spread over the cycle. Duty cycling may be limited to on-peak periods or other specified intervals. Fixed Time Control: Any load can be assigned to operate under time control. Two start and end times may be specified for each individual day of the week. Each relay has its own times specified. Primary demand priority shedding may or may not have an effect on relays under time control. Special Control Features Each relay may use these special control features in addition to using one of the
primary control modes. Analog Control: Up to four external analog inputs and two internal analog signals may be used to provide additional control. A load may be held on or off if a selected analog sensor input is either above or below a set point. Analog control may be used alone or in conjunction with any other mode of control. This permits freeze protection or response to critical temperatures. Demand levels may be used in the same way as analog signals. This permits loads to be locked on or off based on demand. This feature can be used to start an diesel generator. Auxiliary Demand Control: When the auxiliary demand system is operating a load may be assigned to one of the sixteen auxiliary demand priority levels and shed if this level is shed. This control may be used alone or in conjunction with any other mode of control. Illustration of Relay Assignments The diagram to the left illustrates that each relay can be independently assigned to one of the control modes. There are many more possible assignments than relays to provide flexibility. For example, relay 1 is assigned to rotating ring position 3. The rotating ring has been assigned to priority levels 4 through 11 so when priority level 4 is shed one load in the ring will be shed, when priority level 5 is shed two loads in the ring will be shed. The loads in the ring take turns being shed. The large arrows beside the rotating ring are to indicate that the ring may be moved up or down the priority levels as needed. Relay 2 is assigned to priority 14 which places this relay at a high priority. All thirteen lower priority levels will be shed before relay 2 will be turned off. Relay 12 has been assigned to the first position in the variable duty cycle. The variable duty cycle permits a minimum on-time to be specified for each of the 8 positions. The beginning of the on-time for each of the eight positions are spread uniformly over the cycle period specified for the variable duty cycle. The variable duty cycle is associated with a group of priorities. In the illustration it is priority levels 7 through 14. Again the large arrows indicate the group may be moved up or down the priorities as needed. Unless constrained by the minimum on-times, as many of the variable duty cycle relays will be shed as priorities in the associated range. So no variable duty cycle relays will be shed until priority level 7 is shed. Relay 14 has been assigned to fixed time control. Two on and off times for each day may be specified for this relay. Relay 17 is assigned to priority level 6. It also has its operation controlled, in part, by an analog input. Relay 19 is assigned to position 7 in the duty cycle mode. An on-time may be specified for each of the 8 positions in the ring. Duty cycling may be specified to occur during peak periods, specific time periods, or based on analog input signals such as temperature. Relay 17 is shown to have it operation controlled in part by analog inputs. Relay 22 is shown to have its operation defined by the timer as well as an analog input and auxiliary priority 5. Peak Shaving Using a Diesel Generator A Dencor Series 300C Demand Controller is very effective at keeping the demand at, or below, a selected level. For some applications, there may not be enough controlled load to permit demand reduction to the desired level during periods of unusually high demand. In other cases maintaining the selected demand level may require control of some loads for an excessively long period. If a Diesel generator is available it may be operated at peak times to provide additional energy, as needed, to maintain the desired demand level. Customers receiving service on a rate that has a ratchet will find this combination of demand control and Diesel generation especially valuable.
Operating Strategies: Several modes of operation are possible and each requires its own strategy. When it is desired to reduce demand peaks the Diesel may be started and part of the load shifted to the Diesel. If there is a utility power outage, then control must be set at a level that can be supported by the generator. The Series 300C controller with the generator control package has the features needed to support both potential modes of operation. Diesel Power for a Subset of Loads: The basic operating strategy is to have the Dencor Series 300C control demand using the five primary control modes. If there are not enough controlled loads to keep the demand at the desired level, or the controlled loads have been kept off for an excessive period then the Diesel needs to be started. The 300C will signal the Diesel to start and a transfer switch will move selected loads to the Diesel generator. The primary demand control system in the 300C will continue to control the loads supplied by the utility. The auxiliary control system in the 300C will control the loads assigned to the Diesel. Individual demand settings and demand averaging periods may be used for each demand control system. A shorter demand averaging interval may be specified for the auxiliary control system. The demand for both systems is displayed in graph form in real-time. Emergency Power Operation When utility power is lost a transfer switch will start the Diesel. There are several alternatives: Have the transfer switch the total system load to the Diesel. This requires:
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