www. ElectricalPartManuals. com TypeCW Power Relay Descriptive Bulletin Page 1

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1 November, Supersedes DB , dated July, 1971 E, D, C/21 4/DB Westinghouse Eletri Corporation Relay-Instrument Division Newark, N.J. 711 For Exessive or Reverse Power Detetion CW for Single Phase System Appliation in FT- 21 Case Desriptive Bulletin Page 1 TypeCW Power Relay CW for Three Phase System Appliation in FT -11 Case

2 Page 2 Appliation The CW power relay is a self-ontained singlephase indution-dis type relay used to detet exessive or reverse power flow. It is designed to operate at rated voltage. Consequently it is not intended to be a fault deteting relay, sine voltage under fault onditions is generally of redued value. Two types are available: one for single-phase appliation, the other for three-phase appliation. Single-Phase Appliation: The CW relay for single-phase appliation uses line voltage and line urrent. It operates on single-phase watts, with maximum torque ourring when the voltage and urrent are in phase. Three-Phase Appliation: The CW relay for three-phase appliation uses phase-tophase voltage and line urrent, with maximum torque ourring when the relay urrent leads the relay voltage by 3. It operates when the volt-ampere produt (with urrent leading the voltage applied to the relay by 3 ) exeeds the setting of the relay. One CW relay is required for balaned threephase systems, and three are required for unbalaned onditions. Both CW relay types are self-ontained (requiring no external reators), and are available for 12 or 28 volt systems. Single-Phase Appliation This relay operates on single-phase watts. The power to operate it equals the primary single-phase power divided by the urrent and potential transformer ratios. This relay power, expressed as multiples of the seleted tap watts, loates a point on the absissa of the time-power urves (Figures 1 and 2). The relay operating time for various time dial settings an be then observed on the ordinate. Example: Assume: Current transformer ratio, R =2:5=4:1 Potential transformer ratio, Rv=24 12=2:1 Unity power fator, os = 1. Primary -:urrent, I =2 amperes Primary voltage, E = 24 volts Single phase primary power= E I os o = (24) (2) (1.) =48, watts Calulating seondary watts available to operate the CW relay: primary watts =seondary watts R R v 48, =6 watts (4) (2) Using the 2-12 watt relay (single-phase appliation on the 1 watt tap yields (6) =6 multiples of tap watts. 1 Referring to Figure 1, a time dial setting of # 2 yields an operating time of.43 seond. Three-Phase Appliation The CW relay for three-phase system appliation has taps whih represent system seondary three-phase watts divided by..[3 above whih the relay will operate. Consider a three-phase system with 24 volts lineto-line and having the same Rv, R urrent and power fator as in the single-phase example. P3.p=.J3(24) (2) os <!>=831,4 primary watts P - 831, seon d ary watts 3.p- ( 4) (2) To obtain relay response, this value is divided by...[3: P= 1 3} 9 =6 Using 12 watt tap of the 2-12 watt, 12 volt relay, the multiple of tap value would be: m= 6 =5 12 Figure 1 shows an operating time of.52 seonds on the # 2 dial setting. Constrution Features Out-of-phase air gap fluxes reate the neessary operating torque. Sine the voltage is independent of the diretion of power flow, dis rotation is determined by the diretion of line urrent flow. Single-phase appliation: The CW relay for single-phase appliation has a apaitor in parallel with the potential oils and a reator in series with the parallel ombination of apaitor and potential oils... to reate a maximum torque angle when the relay urrent and voltage are in phase. Three-phase appliation: The CW relay for three-phase appliation has a resistor in series with the eletromagnet potential oils to reate maximum torque angle when the relay urrent leads the relay voltage by 3 at system unity power fator. (1) Tap Blok Watt values indiated on the tap blok are the minimum number of single-phase watts required to operate the relay. (2) Time Dial Time settings from indexed positions #'h. to # 11 provide variable operating time values as shown on the time-power urves, Figures 1 and 2. (3) Damping Magnet A high strength alnio magnet ontrols relay operating time at low values of operating urrent. (4) Moving Contat Made of silver and lamped to insulated portion of the indution dis shaft. Eletrial onnetion is made through the spiral spring from the moving ontat through the spring adjuster frame to the relay terminal. The ontats will lose 3 amperes at 25 volts de. (5) Indiating Contator Swith (ICS) The de Indiating Contator Swith unit is a small lapper type devie having a magneti armature to whih leaf-spring mounted ontats are attahed. The armature is attrated to the ore when the oil is energized at or above pik-up value, ausing the moving ontat to bridge two stationary ontats, ompleting the trip iruit. The ICS ontats are onneted in parallel with the main relay ontats, and relieve them of arrying heavy trip urrents. The main relay ontats will lose 3 amperes at 25 volts de, and the ICS ontats will safely arry this urrent long enough to trip a iruit breaker. When the ICS.is energized, two figures on the armature yolk deflet a leaf-spring loated on the front of the swith, allowing the operation indiator target to drop. The target is reset external to the ase by a push rod loated at the bottom of the relay ase over. Taps on the front of the relay provide onnetion for either.2 (left) or 2. (right) ampere de minimum pik-up setting. When the protetive relay energizes a WL relay rated 125 or 25 volts de, the.2 ampere tap is reommended. The 2. ampere tap is used on 24 or 48 volt de iruits. (6) Spare Tap Srew To avoid open-iruiting urrent transformers when hanging from one value to another, the spare tap srew is inserted into the desired new tap before the other is removed. (7) Stationary Contat Made of silver, with suffiient wipe to assure positive ontat. On double trip relays, vernier adjusting srews are provided on the stationary ontat assembly to provide the desired ontat wipe. (8) Contat Plate In fast breaker relosing shemes whih require quik-opening relay ontats, the metal ontat plate is reversed to hold the stationary ontat fixed against the bakstop.

3 Desriptive Bulletin Page 3

4 Page 4 Time Power Curves Type CW Low Watt Relays Typial Time Curves <J) 1".3 (.).2.<:: Q) E f= Figure 1 Multiple of Tap Watts Setting Produt Unit 8 1 Two adjustments are required to set the CW relay: 1. Seletion of the desired urrent tap on the eletromagnet, and 2. Setting of the time dial for the required time of operation as shown on the time-power urves, Figures 1 and Type CW High Watt Relays Typial Time Curves <J) -g.3 (.).2 Q) E 2 f= ' A6 Figure 2 CW Relay (Single Phase) Multiple of Tap Watts The power to operate the relay equals the primary power divided by the urrent and potential transformer ratios. CW Relay (Three Phase) The CW relay for three-phase appliations has taps whih represents single phase watts multiplied by '1/ 3. The power to operate the the relay equals the three phase primary power divided by the quantity ( i3 times the urrent and potential transformer ratios). '1/3 P/ TAP=R R v P A61

5 Charateristi Settings Operating Ranges Single-Phase Appliation Volts Single-Phase Watts Range Taps Burden Data on 6 Hertz CW Relay Relay Potential Ciruit Appliation Range: Voltage Volt - Watts Amperes 5.4 Single Phase Three Phase Current Coil Ratings Relay Range: Watts A Amperes Continuous Three-Phase Appliation Volts: Line Line ( I L V LL ),[3 Single Phase Watts Range Taps Current Lags by: 26.5" zoo 6 6 Shipping Weights and Carton Dimensions Current Ciruit Current Relay Volt- Current Tap Amperes Lags by: 5 Amp Amp T 5 Amp Amp T 35 5 Amp Amp T Trip Ciruit Data ICS Tap: Coil Rating in Amps: De Resistane 1-Seond Amps De ""- -,.-_ --'' ont ;' in u o u s 1 ' -: ;; - -S ē - ond - -, --- in Ohms.2 2. CW Relay Flexitest Weight, Lbs., (kg) Approx. Appliation Case Size Net Shipping Single Phase FT (5) Three Phase FT-11 7 (3.2) Potential Coil Ratings CW relay potential iruits will withstand 11% of rated voltage, ontinuously. 14 (6.4) 1 (4.5) Domesti Shipping Carton Dimensions: Inhes (mm) 9 X 12 X 13 (229 X 35 X 33) 9 X 9 X X 229 X 254) Desriptive Bulletin Page 5

6 Page 6 Internal Wiring For Single-Phase Appliation, SPST Contats-FT -21 Case r I I I L 8 8 Figure 3 183A773-Sub. 1 For Three-Phase Appliation DPST ontats-ft-11 Case ICS Figure 5 184A554-Sub. 1 Indiating Contator Swith Reator Indution Unit Chassis Operated Shorting Swith Current Test Jak Flexitest Swith Case Terminal Indiating Contator Swith Indution Unit Chassis Operated Shorting Swith Current Test Jak Flexitest Swith Case Terminal For Single-Phase Appliation, DPST Contats-FT-21 Case ICS Figure 4 183A774-Sub. 1 For Three-Phase Appliation-FT -11 Case w Figure 6 183A776-Sub.1 Indiating Contator Swith Reator Indution Unit Chassis Operated Shorting Swith Current Test Jak Flexitest Swith Case Terminal Indiating Contator Swith Indution Unit Chassis Operated Shorting Swith Current Test Jak Flexitest Swith Case Terminal..

7 External Wiring of One Type CW Relay on a Single Phase System Figure ' Ol Ci Q_ Station Bus 184A81-Sub. 2 External Wiring of 3 Type CW Relays on a Three Phase System Note: For Balaned 3-Phase Conditions, Only One Relay is Required..., u 2' Ol o_ Q_ J 2 3 Station Bus Figure 8 184A811-Sub. 3 Ph1 Ph 2 Ph 3 Devie Chart Number 32-diretional power relay, Type CW 53-power iruit breaker ICS-indiating ontator swith 52TC-breaker trip oil 52a-breaker auxiliary oil Desriptive Bulletin Page 7 =52a!52\ Neg Pos-- D Bus--- Neg ' 32 3

8 Desriptive Bulletin Page 8 Further Information Styles and Ordering Information Pries Flexitest Case Instrutions Other protetive relays Westinghouse Eletri Corporation Relay-Instrument Division Newark, N.J. 711 Tehnial Data 41-2 T WE A Prie List 41-2 P WE A Desriptive Bulletin Single-Phase Appliation: Instrution Leaflet Three-Phase Appliation: Instrution Leaflet Seletor Guid e 41- A & B