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0611DB1107 03/2012 Data Bulletin Replaces 0611DB1107 12/2011 Shedding Non-Priority Loads with PowerPact™ H-, J-, and L-Frame Circuit Breakers with Micrologic™ Trip Units Introduction Load-shedding is one of the active energy efficiency features of the PowerPact™ H-, J-, and L-frame circuit breakers with Micrologic™ electronic trip units. Load-shedding (preventing some non-priority loads from being supplied during a certain period of time) can be used to limit power to an entire electrical installation. The advantages are: • • • lower energy consumption cost optimization improved system availability Load-shedding is used to: • prevent overload tripping: if the load approaches the maximum load threshold, a load-shedding order on previously selected loads can help prevent a general power failure throughout the installation (improved availability) • allow a lower level power contract, while allowing all the devices to operate correctly • carry the consumption forward to an off-peak tariff period (cost optimization. Two load-shedding solutions are provided: • • Figure 1: “reflex” load-shedding using a local order “centralized” load-shedding using a remote order Load Shedding Centralized Load Shedding 06114925 06114924 Reflex Load Shedding PC or PLC controller Ethernet EGX100 PowerPact Circuit Breaker Modbus SDx IFM FDM121 Micrologic 5.3 E PowerPact Circuit Breaker Micrologic 5.3E Trip Unit BSCM Circuit Breaker Boiler Priority Loads Non-Priority Load © 2011–2012 Schneider Electric All Rights Reserved ™ Shedding Non-Priority Loads Data Bulletin 0611DB1107 03/2012 Reflex Load-Shedding Description The reflex load-shedding order is generated locally by the PowerPact H-, J-, or L-frame circuit breaker itself using the Micrologic electronic trip unit. The Micrologic E electronic trip unit (energy measurement) is used to manage alarms based on the monitoring of electrical variables such as the instantaneous current, the demand power (Pdmd) or even the frequency. An activation (pick-up) threshold (SA) with its time delay (TA) and a deactivation (drop-out) threshold (SD) with its time delay (TD) are associated with each alarm. The time delays are independent and can be set from 1 s to 3000 s. The following figure illustrates the high alarm activation condition: High Alarm Activation Condition 06114926 Figure 2: SA SA TA SD TD 1 TA Activation threshold Activation time delay Deactivation threshold Deactivation time delay Alarm: activation zone (green) SD TD (t) 1 06114030 SDx Module The detection of a threshold triggers load shedding of the load connected to the threshold. Shedding the load connected to threshold prevents the circuit breaker from tripping and therefore improves availability. The reflex load-shedding order is sent to the load-shedding contactor through the SDx module installed in the PowerPact H-, J-, or L-frame circuit breaker. After configuring the thresholds, all that is required is to assign the alarm to output 2 on the SDx module (as output 1 is already assigned to the SDT long delay tripping notification). This load-shedding contactor (2-pole NC) cuts off the non-priority feeders. Products used Products needed to set up load shedding are shown below. For catalog numbers, see the PowerPact H-, J-, and L-Frame catalog, 0611CT1001. Table 1: Products Required for Ethernet Connection Product 2 Description Circuit Breaker PowerPact™ H-, J-, or L-Frame Circuit Breaker Micrologic Trip Unit Electronic trip unit with energy measurement: Micrologic E SDx Indication relay module Cx Two-pole contactor (2-pole NC) 20 A © 2011–2012 Schneider Electric All Rights Reserved 0611DB1107 03/2012 Shedding Non-Priority Loads Data Bulletin Configuration The alarms are configured using the RSU software (downloadable from schneider-electric.com) Example 1 Load-shedding based on the instantaneous current threshold of the phase (I1). The detection of an instantaneous current high threshold overrun on a phase indicates an overload on that phase. Shedding a single-phase load connected to the phase prevents the circuit breaker from tripping on overload (long time delay) and therefore improves availability. Example 1 Alarms Setup 06114927 Figure 3: The load-shedding order is given as soon as the phase 1 current exceeds 80 A for more than 20 s. This order will be maintained as long as the phase 1 current does not fall below 30 A for more than 10 s. NOTE: To avoid beat phenomena, it is recommended that the difference between the high threshold (80 A) and the low threshold (30 A) should be greater than the current consumed by the shed load. Example 2 Load-shedding based on a total demand power threshold (Pdmd). The detection of a demand total power high threshold overrun indicates an overload on this installation. Load shedding prevents the subscribed power from being exceeded and therefore optimizes costs. Example 2 Alarms Setup 06114928 Figure 4: © 2011–2012 Schneider Electric All Rights Reserved 3 Shedding Non-Priority Loads Data Bulletin 0611DB1107 03/2012 The load-shedding order is given as soon as the total demand power exceeds 53 kW for more than 70 s. This order will be maintained as long as the total demand power does not fall below 20 kW for more than 15 s. Example 3 Load-shedding based on frequency threshold (f). The detection of a network frequency low threshold overrun in the event of the installation being operated by a diesel generator indicates an imbalance between the demand and the capacity of the generator. Load shedding makes it possible to redress the balance and therefore to improve availability. Example 3 Alarms Setup 06114929 Figure 5: The load-shedding order is given as soon as the frequency falls below 48 Hz for more than 2 s. This order will be maintained as long as the frequency does not rise above 49.5 Hz for more than 5 s. 06114930 Wiring Diagram a 230 V SDT output 1 SD3 Cx output 2 SD2 A1 A2 SD4 SDx Q SD1 a 4 © 2011–2012 Schneider Electric All Rights Reserved 0611DB1107 03/2012 Shedding Non-Priority Loads Data Bulletin Test Test whether the reflex load-shedding solution has been implemented by using the LSU (Local Simulation Utility) software. This software, which is available from www.schneider-electric.com, can be used to simulate the electrical variables (I, V, f, THD, phase shift angle phi). The USB port is connected using the maintenance module. Connection Using the USB Port 06114931 Figure 6: 1. Standard USB cable connecting the maintenance module to the PC 2. Maintenance module power supply unit 3. Micrologic cable connecting the maintenance module to the trip unit test socket From the LSU software, a current is simulated on phase 1 (I1=83 A for example) and at the end of the activation time delay (20 s), it is noted that output 2 on the SDx module changes to 1 and therefore supplies the coil of the load shedding contactor (Cx) that will cut off the non-priority feeders. To change the SDx module output back to 0, a current of less than 30 A must be simulated on phase 1 for at least 10 s. The same procedure can be followed for load-shedding solutions based on the power or frequency threshold. Centralized Load Shedding Description The centralized load-shedding order is generated remotely by the controller (PC or PLC). 06114932 The controller is used to generate load-shedding orders based on monitoring the electrical variables of the entire electrical installation, taking the time bands, operating constraints or even process-related information into consideration. BSCM The centralized load-shedding order is sent to the BSCM installed in the PowerPact H-, J-, or L-frame circuit breaker through the Modbus™ communication network. The BSCM is connected to the communicating motor operator. The communicating motor operator is the actuator that opens or closes the circuit breaker. 06114933 The FDM121 front display module can be added as an optional extra. In addition to displaying measurements, alarms and operating information, the FDM121 can be used to give a local order to open/close the PowerPact H-, J-, or L-frame circuit breaker. FDM121 In remote mode, only orders from the controller are taken into account. In local mode, only orders from the display unit are taken into account. This ensures, for example, that no unwanted circuit breaker opening orders are received and that the closed position is maintained during a critical operation (backup, transfer of sensitive data, etc.). © 2011–2012 Schneider Electric All Rights Reserved 5 Shedding Non-Priority Loads Data Bulletin 0611DB1107 03/2012 Products used Products needed are shown below. For catalog numbers, see the PowerPact H-, J-, and L-Frame catalog, 0611CT1001. Table 2: Configuration Figure 7: Products Required for Ethernet Connection Product Description Circuit Breaker PowerPact™ H-, J-, or L-Frame Circuit Breaker with Micrologic Electronic trip unit MTc Communicating motor operator BSCM Breaker Status Control Module NSX Cord Wire length L= 1.3 m IFM Modbus interface module FDM121 Front display module EGX100 Modbus/Ethernet communication gateway No special configuration is required for the Micrologic trip unit. The loadshedding order (circuit breaker opening/closing) is sent by the controller to the BSCM module through the Modbus network. The configuration of the BSCM module Modbus circuit breaker opening/closing orders is specified in the Modbus Communication—User Guide (48940-328-01). Ethernet Connection Ethernet white D1 D0 RS485 TX RX white e 06114934 blue LX TX RX 100 blue 24 V 24 V Rx- Rx+ Tx- Tx+ Modbus Switches 0V 24V 2 wire UP/ON DOWN/OFF FDM121 NSX cord B4 HL + - a (220/240 V) BSCM MTc Q 0 I A1 auto manu a 6 © 2011–2012 Schneider Electric All Rights Reserved 0611DB1107 03/2012 Shedding Non-Priority Loads Data Bulletin Test Test whether the centralized load-shedding solution has been implemented by using the RCU (Remote Control Utility) software. This software, which is available from schneider-electric.com, can be used to open/close the PowerPact H-, J-, or L-frame circuit breaker using the communicating motor operator. Connection to the PC Ethernet port is through the Modbus/Ethernet EGX communication gateway. In the main set-up menu, go to the User profile submenu and choose “control”. The control tab is now available and can be used to check that the communicating motor operator is operating correctly over the Modbus network. User Profile Submenu 06114935 Figure 8: Conclusion The reflex load-shedding solution using a local order with PowerPact H-, J-, or L-frame breaker provides: • a reduction in capital expenditure, as its purchase price is lower than that of a traditional solution: the cost of a PowerPact H-, J-, or L-frame circuit breaker with a Micrologic E trip unit (energy measurement) + SDx module is similar to the cost of a PowerPact H-, J-, or L-frame circuit breaker without the measurement function + Power Meter + I/O + CT. The difference is the cost of installing/wiring/testing the CTs, which is included in the PowerPact H-, J-, or L-frame circuit breaker. • a reduction in operational expenditure, due to optimized energy costs and to the improved availability provided by the load-shedding function. NOTE: As standards, specifications and designs change from time to time, please ask for confirmation of the information given in this publication. © 2011–2012 Schneider Electric All Rights Reserved 7 Shedding Non-Priority Loads Data Bulletin Schneider Electric USA, Inc. 3700 Sixth St. SW Cedar Rapids, IA 52404 USA 1-888-778-2733 www.schneider-electric.us 8 0611DB1107 03/2012 Electrical equipment should be installed, operated, serviced, and maintained only by qualified personnel. No responsibility is assumed by Schneider Electric for any consequences arising out of the use of this material. Square D™ and Schneider Electric™ are trademarks or registered trademarks of Schneider Electric. Other trademarks used herein are the property of their respective owners. © 2011–2012 Schneider Electric All Rights Reserved