Eaton Cooper Power Series Installation, Operation And Maintenance Manual

Also see for COOPER POWER SERIES: Installation and operation instructions Installation instructions Installation instructions Installation and operation instructions Operation instructions

Contents

Eaton Cooper Power Series Installation, Operation And Maintenance Manual Manual pdf 33 page image

Basic control operationsSet voltageThe set voltage is the voltage level to which the controlwill regulate on the 120 V or 240 V base. Since the controlperforms ratio correction in the firmware, this value willtypically be set for 120.0 V/240.0, unless it is desired tooperate at a voltage level higher or lower than nominal. Forproper operation, the ratio-correcting transformer, located onthe back panel of the control enclosure, must also be set forthe correct tap as shown on the regulator nameplate.BandwidthThe bandwidth is defined as that total voltage range, aroundthe set voltage, which the control will consider as a satisfiedcondition. As an example, a 2 V bandwidth on a 120 V setvoltage means the time delay timer will not activate untilthe voltage is below 119 V or above 121 V. When the voltageis in-band, the band edge indicators are off and the timer(time delay) is off. Selection of a small bandwidth will causemore tap changes to occur, but will provide a more tightlyregulated line. Conversely, a larger bandwidth results infewer tap changes, but at the expense of better regulation.Selection of the bandwidth and time-delay settings shouldbe made recognizing the interdependence of these twoparameters.Time delayThe time delay is the period of time (in seconds) that thecontrol waits from when the voltage first goes out-of-bandto the time when a tap change is issued. If a rapid responseis required, a shorter setting should be used. If severaldevices on the same line are to be coordinated (cascaded),different time-delay settings will be required to allow thedevices to operate in the desired sequence. Proceedingfrom the source, each device should have a longer timedelay than the preceding device. A minimum 15-seconddifference between regulators located on the same phaseon the same feeder is recommended. The delay allowsthe upstream device to perform its operations prior to thedownstream device reacting. The time-delay setting of avoltage-minimizing, activated capacitor control should be setthe same as a regulator control. Alternate time delays areavailable with the voltage limiter feature. Refer to Section 6:Control Features: Voltage limiter for more information.Line drop compensation, resistance and reactancesettingsQuite often regulators are installed some distance from thetheoretical load center (the location at which the voltage isto be regulated). This means the load will not be served atthe desired voltage level due to the losses (voltage drop) onthe line between the regulator and the load. Furthermore,as the load increases, line losses also increase, causingthe lowest voltage condition to occur during the time ofheaviest loading.To provide the regulator with the capability to regulateat a projected load center, the control has line-drop-compensation elements within it. This circuitry usuallyconsists of a current transformer (CT), which produces acurrent proportional to the load current, and resistive (R) andreactive (X) elements through which this current flows. Asthe load increases, the resulting CT current flowing throughthese elements produces voltage drops, which simulate thevoltage drops on the primary line.Within the control, the input current is sampled and is usedin a computer algorithm which calculates the respectiveresistive and reactive voltage drops based upon the line-drop-compensation values programmed into the control atFC 4 and FC 5 (or FC 54 and FC 55 for reverse power flowconditions). This is an accurate and economical means ofdeveloping the compensated voltage.To select the proper R and X values, the user must knowseveral factors about the line being regulated.Regulator configurationThe control is designed to operate on wye (star)-connectedand delta-connected regulators. Regulators connected line-to-ground (wye) develop potentials and currents suitable fordirect implementation in the control. Regulators connectedline-to-line (delta) develop a potential-to-current phase shiftwhich is dependent upon whether the regulator is definedas leading or lagging. The phase shift must be known by thecontrol to permit accurate calculations for correct operation.This is accomplished by entering the proper option at FC 41:Wye, Delta Lagging, or Delta Leading. See Section 3:Initial Control Programming: Determination of leadingor lagging in delta-connected regulators for moreinformation on setting this parameter.Control operating modesThe CL-7 control supports three modes in which the controlresponds to out-of-band conditions, permitting use of themode that best fits the application. The three modes areSequential, Time Integrating, and Voltage Averaging. Themode setting can be selected by scrolling within FC 42 orthrough Settings > Configuration in the menu structure.Sequential modeThis is the standard mode of response. When the loadvoltage goes out-of-band, the time-delay circuit is activated.At the end of the time delay, a tap change is initiated.After each tap change, a 2-second pause occurs to permitthe control to sample the voltage again. This sequencecontinues until the voltage is brought into band, at whichtime the timing circuit is reset. Whenever the voltage goesin-band, the timer is reset.Time-integrating modeWhen the load voltage goes out-of-band, the time-delaycircuit is activated. At the end of the time-out, a tap changeis initiated. After each tap change, a 2-second pause occursto permit the control to sample the voltage again. If thevoltage is still out-of-band, another tap change is performed.This sequence continues until the voltage is brought27INSTALLATION, OPERATION, AND MAINTENANCE INSTRUCTIONS MN225003EN April 2018CL-7 Voltage Regulator Control