41-492.3A

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14

41-492.3A

between 60° and 80° by adjusting the potentiom-eter between its minimum and maximum valuesrespectively or for 89° by open circuit ing theresistor. The factory sett ing is for a maximumtorque angle of 75° current lagging voltage.

2.1.1 Auto-transformer

The auto-transformer has three taps on its mainwinding, S, which are numbered 1, 2, and 3 onthe tap block. A ter tiary winding M has four tapswhich may be connected additively, or subtrac-t ively to inversely modify the 9 sett ing by anyvalue from -18 to +18.

The sign of M is negative when the R lead isabove the L lead. M is positive when L is in a taplocation which is above the tap location of the Rlead. The M setting is determined by the sum ofper unit values between the R and L lead. Theactual per unit values which appear on the tapplate between taps are 0, .03, .09 and .06.

The au to - t rans fo r mer makes i t poss ib le t oexpand the basic range of the TABF by a multiplier

of . Therefore, any relay ohm setting can be

made within ±1.5 percent from 1.3 to 36.7 ohmsby combining the compensator taps of TABF with

auto-transformer taps S and M.

There is no auto-transformer to modify TABR taps.

2.1.2 Cylinder Unit

The device which acts to initiate blocking is a fourpole cylinder unit which is connected so that onepole pair voltage leads the other by 90° and oper-ates as a two-phase induction motor.

Mechanically, the cylinder unit is composed offour basic components: a die-cast aluminumframe, an e lect romagnet, a moving elementassembly, and a molded bridge.

The frame serves as the mounting structure forthe magnetic core. The magnetic core whichhouses the lower pin bearing is secured to theframe by a lock ing nut . The bear ing can bereplaced, if necessary without having to removethe magnetic core from the frame.

The electromagnet has two ser ies-connectedco i l s m o un t e d d i am e t r i ca l l y o pp o s i t e on eanother, to excite each set of poles, and two

locating pins. The locating pins are used to accu-rately position the lower pin bear ing, which ismounted on the frame, with respect to the upperpin bearing, which is threaded into the bridge.The electromagnet is secured to the frame byfour mounting screws.

The moving element assembly consists of a spi-ral spring, contact carrying member, and an alu-minum cyl inder assembled to a molded hubwhich holds the shaft. The shaft has removabletop and bottom jewel bearings. The shaft r idesbetween the bottom pin bearing and the upperpin bearing which is adjustable to .025 inch fromthe top of the shaft bearing. The cylinder rotatesin the air gap formed by the electromagnet andthe magnetic core. The stops for the moving ele-ment contact arm are an integral par t of thebridge.

The bridge is secured to the electromagnet andframe by two mounting screws. In addit ion toholding the upper pin bearing, the bridge is usedfor mounting the adjustable stationary contacthousing. The stationary contact housing is heldin posit ion by a spring type clamp. The spr ingadjuster is located on the underside of the bridgeand is attached to the moving contact arm by aspiral spring. The spring adjuster is also held inplace by a spring-type clamp.

In the absence of a disturbance, ZOS contacts

(Figure 3) are closed and the electrical connec-tion is made through the spiral spring adjusterclamp to shor t-circuit the telephone type relaycoil (OS). When operating torque causes thecontact to open, then the short-circuit is removedfrom across OS, permitting i t to become ener-gized.

2.2 TELEPHONE RELAY

The telephone-type relay unit, OS, is a slow-to-operate type. An electromagnet attracts a right-angle iron bracket which in turn operates a set ofmake-and-break contacts. The delay in operationis obtained by a copper slug which acts as a lagcoil and delays the build-up of magnetic lines offorce in the core.

When the telephone-type relay is energized, bythe opening of the cylinder unit contacts, it opensits several sets of contacts which are normally

S1 M±--------------

3

41-492.3A

connected in ser ies wi th the KD re lay three-phase unit contacts, and thus prevents complet-ing the trip circuit during an out-of-step condition(Figure 2).

3.0 OPERATIONOne fundamental difference between a three-phase fault and an out-of-step or out-of-synchro-nism condition is that a fault suddenly reducesthe voltage and increases the current, whereasduring the approach of an out-of-step condition,the voltage and current changes are compara-tively gradual. When the line impedance to theapparent fault (ZF) is less than the compensator

setting (ZC). IZC (compensator output voltage)

becomes greater than the line voltage drop to thefault. This reverses the compensated voltage andthereby reverses the polar i ty of the vo l tageapplied to one pole pair and contact-openingtorque is produced in the cyl inder unit. Underout-of-step conditions, the apparent impedancemeasured by the relay anywhere near the electri-ca l cente r s tar ts a t a h igh va lue, gradua l l ydecreases to a much lower value, and then grad-ually increase again to a higher value, and thusthe system goes through a complete beat oscilla-tion. On the other hand, if the disturbance is afault, the impedance seen by the relay will sud-denly drop to a much lower value, and then eitherretain this value or slightly increase due to theef fec ts o f fau l t res is tance, un t i l the fau l t i scleared.

The KS-3 relay takes advantage of the distinctionbetween a fault and an out-of-step condit ion.Under out-of-step conditions, the KS relay willoperate followed after a short time delay by zone2 KD relay operation, as the apparent short cir-cuit drifts toward the relay. In case of a fault, theKS-3 as well as zone 2 and zone 1 (depending onfault) will operate within a very shor t time, andwill not follow the sequence described for an out-of-step condition.

3.1 COMPENSATOR

Sensitivity to the out-of-step condition is pro-vided by compensators designated as TABF and

TABR in Figure 2. Each compensator is propor-

t ioned so that i ts mutual impedance, ZC, has

known and adjustable values from T = 1.5 ohm toT = 10.0 for forward reaching compensators andfrom T = .87 ohm to T 5.8 for reverse reachingcompensators in 30 percent steps. Compensatormutual impedance ZC is defined as the ratio of

secondary induced voltage to pr imary currentand is equal to T. The secondary (voltage) wind-ing of the compensator is in ser ies wi th theapplied voltage and vectorially subtracts a valuefrom the applied voltage which is proportional toIZ where I is relay current. The subtraction occurs

for forward reaching compensator (TABF) voltage

during fault or out-of-step condition which appearto the relay as faults in forward direction. Forreverse reaching compensator (TABR), its sec-

ondary voltage is vectorially added for the condi-t ion descr ibed above. For reverse appear ingfaults, the relationships between relay voltageand compensator secondary voltages are corre-spondingly reversed. The reverse looking com-pensa tor (TA B R ) i s r equ i red t o p roduce an

impedance characteristic which will be concentri-cal with the three-phase unit of the KD familyrelay.

When the line impedance (to the electrical centeror to a fault ZF) is less than the compensator set-

ting (ZC), IZC becomes greater than the line volt-

age drop to the electrical center or fault. Thisreverses the phase of one of the voltages appliedto the relationship cylinder unit and an operatingtorque is produced.

4.0 CHARACTERISTICSReferring to Figure 4, the scheme of operation isdescr ibed below. The impedance circle of therelay is set to encircle the second zone KD relaythree-phase unit. The difference between the twocircles provides a margin in ohms sufficient togive the telephone-type relay t ime to operatebefore the swing condition enters the character-istic circle of zone 2 after having entered the cir-cle of KS-3 relay. The telephone-type relay willopen, w i th in 3 to 4 cyc les, i t s OS con tac ts

located between the 68/ 4 and 68 /5 te r mina ls

shown in the tr ip c ircuits section of Figure 2.Thus all of the OS contacts operate to block trip-ping and also to prevent the short-circuiting and

4

41-492.3A

de-energizing of the OS coil as the zone 2 con-tacts close. When zone 2 operates before OS, asit does for a three-phase fault condition, a short-circuit across the coil, OS, is completed throughthe KD relay, and DZ2 and OS is not energizedeven though the ZOS contacts do open.

In case of ground faults, DO and IO operate and

maintain shor t circuit across OS coil throughDZG.

4.1 GENERAL CHARACTERISTICS

Impedance settings in ohms for forward reachcan be made for any value from 1.27 ohms to36.7 ohms in steps of 3 percent.

The maximum torque angle, which is set for 75°at the factory, may be set for any value from 60°to 80°. A change in maximum torque angle willproduce a slight change in reach for any givensetting of the relay. Referr ing to Figure 5 notethat the compensator secondary voltage outputV, is largest when V leads the primary current, I,by 90°. This 90° relationship is approached, if thecompensator loading resistor is open-circuited.The effect of the loading resistor, when con-nected, is to produce an internal drop in the com-pensator, which is out-of-phase with the inducedvoltage, compensator voltage IZC. Thus the net

voltage V is phase-shifted to change the com-pensator maximum torque angle. As a result ofthis phase shift the magnitude of V is reduced, asshown in Figure 5.

Tap markings on the tap plate are based upon a75° compensator angle setting. If the potentiom-eters PF and PR are adjusted for some othermaximum torque angle, the nominal reach is dif-ferent than indicated by the taps. The reach, Z,varies with the maximum torque angle θ, as fol-lows:

TAP PLATE MARKINGS

4.2 SETTING CALCULATIONS

The type KS-3 relay requires an ohm setting highenough that its impedance circle completely sur-rounds the impedance circle of the Zone 2 KD-type relay three phase unit with sufficient marginto accommodate the fastest swing rate. Usually a2 ohm larger radius (ZDF), (Figure 4) for KS-3

relay will suffice. The ZDF reach which should be

equal to reverse reach is selected from the sevena va i l a b l e t a p s o f T r ev e r s e r e a c hcompensators .87, 1.16, 1.45, 2.03, 2.9, 4.06,5.8.

The forward reach ZL is set according to the fol-

lowing formula:

ZL = (ZZone2 + 2 ohms) (1)

The equation (1) is applicable where maximumtorque angle of KS-3 is the same as of the KD-type relay.

The more general formula for setting the forwardreach is required where the maximum torqueangle of the KS-3 relay is adjusted for an angle,which is different from 75° to match the angle ofthe 3-phase unit of KD relay. When we assumethat ZL setting is desired which is greater by 2

ohms than the second zone impedance relay set-ting then the general formula for setting in ohmsis:

The terms used in this formula are defined as fol-lows:

ZLθ =the desired ohmic forward reach of the relay

at an angle θ.

Z TS θsin1 M±( ) 75°( )sin

------------------------------------------=

TABF (Forward)1.5 2.0 2.5 3.51 5.0 7.02 10.0,, , ,,,--------------------------------------------------------------------------------------

TABR (Reverse)87 1.16 1.45 2.03 2.90 4.06 5.8, ,,,,,-------------------------------------------------------------------------------------------

Values between taps M

.03 .09 .06,-----------------------------±

Current Circuit Rating in Amperes

Tap Setting Continuous 1 Second

107.025.03.512.52.01.5

57

1010101010

240240240240240240240

ZLθ ZLθsin75sin

------------- ZZone 2 2 ohms+( )= =

5

41-492.3A

ZL = the forward reach tap plate setting.

where T is TAF and TBF compensator settings

S is SF auto-transformer primary tap value

θ – relay maximum torque angle

For a standard setting of 75°

(2)

M is MF- Auto-transformer secondary tap value

(This is a Per unit value and is determined by thesum of the values between the “L” and the “R”leads. The sign is positive when “L” is above “R”and acts to lower the Z setting. The sign is nega-tive when “R” is above “L” and acts to raise the Zsetting).

Reverse reach is calculated by formula

(3)

where T are TAR, TBR compensator settings

θ - relay maximum torque angle for a standardsetting of 75°

then

SAMPLE CALCULATIONS

An optimum forward setting is obtained by thefollowing procedure:

Step 1. Establish margin to accommodate thefastest swing rate. Usually this marginis selected as 2.03 ohms, other valuesthat can be selected are 5.8, 4.06, 2.9,1.45, 1.16, and 0.87.

The selected margin determines thereverse reach setting.

Step 2. Determine the desired forward reachZL, which is equal to ZZone2 + 2 ohms.

No te tha t 2 .03 ohms was se lec tedabove as a safe margin for identifying asystem swing and is not influenced bythe magnitude of ZZone 2.

Step 3. Using Table 1, select optimum setting

for the forward reach of the relay as fol-lowing:

a) Locate a table value for the forwardreach Z (it will always be within 1.5% orless of the desired value).

b) Read off the table “S, “T”, and “M”set t ings. “M “column inc ludes add i-tional information for “L” and “R” leadssettings for the specified “M” value.

c) Recheck the obtained S, T, M set-tings by using equation (1).

Example I

Step 1. Select 2.03 ohms tap f rom avai lablereverse reach compensator sett ings.Hence TAR = TBR = 2.03 ohm, assum-

ing Zone 2 settings is 7 ohm at 75°.

Step 2. Using equation 1, establish forward reachof the relay.

Z = 7 + 2 = 9 ohms

Step 3. a) From Table 1, we find the 8.9 ohmsas the closest value to 9.0 ohms.

b) Then we read off T, S, and M values.T = 10.0, S = 1, M = +.12

Hence TAF = TBF = 10.0

SF = 1

MF = +.12

and “L” lead should be connected over“R” lead. “L” lead is connected to “.09”tap and “R” lead to “0” tap.

c) Recheck the settings

Example II

Assume that the Zone 2 three phase unit settingis 7 ohms at 60°, and KS-3 recalibrated to 60°.

Step 1. Select reverse reach as 2.03 ohmswhich in a relay when recalibrated to a60 degree angle will be calculated perEq. 2.

TS1 M±--------------

θsin75sin

-------------- 1=

ZRT θsin

75sin--------------=

θsin75sin

-------------- 1=

Z ST1 M+-------------- 1x10

1 .12+----------------- 8.93= = =

6

41-492.3A

Set TAR = TBR = 2.03 (nearest value to

2 ohms at 60°).

Step 2. Find ZLO = ZZone2 + 2 = 9.

Correct Z = 9 ohms for recalibration ofthe compensator to 60°.

Step 3. a) From Table 1, find value closest to10.04 ohms which is “10.0”.

b) Then we read off T, S, M values as

Hence TAF = TBF = 10.0

SF = 1

MF = 0

All “L” and “R” leads should be corrected to tapsmarked “0” and “0”.

Recheck the settings

5.0 SETTING THE RELAYThe KS-3 relays require settings for the two com-pensators TABF, TABR, the auto-transformer pri-

mar y (SF) and secondar y (MF). A l l o f these

settings are made with taps on the tap plate.

5.1 COMPENSATORS TABF AND TABR

Each set of compensator taps ter minates ininserts which are grouped on a socket and formapproximately three quarters of a circle around acenter insert which is the common connection foral l of the taps. Electrical connections betweenthe common insert and tap inserts are made witha link held in place by two connector screws, onein the common and one in the tap. A compensa-tor tap setting is made by loosening the connec-tor screw in the center. Remove the connectorscrew in the tap end of the link, swing the linkaround until it is positioned over the insert for thedesired tap setting, replace the connector screwto bind the link to this inser t, and retighten theconnector screw in the center. As the link and

connector screws carry operating current, besure that the screws are tight but not so tight asto break the tap screw. There are four T taps, twofor long reach and two for shor t reach. The Ttaps connected in a way to use delta current.

5.2 AUTO-TRANSFORMER PRIMARY (SF)

Primary tap connections are made through a sin-gle lead for each transformer. The lead comesout of the tap plate through a small hole locatedjust below or above the taps and is held in placeon the tap by a connector screw.

An “S” setting is made by removing the connectorscrew, placing the connector in position over theinsert of the desired setting, and then replacingand tightening the connector screw. The connec-tor should never make electr ical contact withmore than one tap at a time.

5.3 AUTO-TRANSFORMER SECONDARY (MF)

Secondary tap connections are made throughtwo leads identified as L and R for each trans-former. These leads come out of the tap plateeach through a small hole, one on each side ofthe vertical row of “M” tap inserts. The lead con-nectors are held in place on the proper tap byconnector screws.

An “M” setting can be made for values from -.18to +.18 in steps of .03. The value of a setting isthe sum of the numbers that are crossed whengoing from the R lead position to the L lead posi-tion. The sign of the “M” value is determined bywhich lead is in the higher posit ion on the tapplate. The sign is positive), if the L lead is highera n d n e g a t i ve i f t h e R l e a d i s h i g h e r .

An “M” sett ing may be made in the fol lowingmanner. Remove the connector screws so thatthe L and R leads are free. Refer to Table 1 todetermine the desired “M” value. Neither leadconnector should make electrical contact withmore than one tap at a time.

5.4 LINE ANGLE ADJUSTMENT

Maximum sensit ivity angle is set for 75° + 5°(current lagg ing vo ltage) in the factory. Thisadjustment need not be disturbed for line anglesof 65° or higher. For line angles below 65°, setfor a 60° maximum sensitivity angle by adjusting

ZRT θsin

75sin-------------- 2.03 60°sin

75sin----------------- 1.82= = =

Z 9 75°sin60°sin

----------------- 9 .965.866------------ 10.04 ohms= = =

Z ST1 M±-------------- 1x10

1 10+---------------- 10.0 ohms= = =

7

41-492.3A

Table 1: TABLE OF FORWARD REACH SETTINGS

S = 1 S = 2 S = 3 “M”Lead

Connection

TAF&

TBF 1.5 2.0 2.5 3.51 5.0 7.02 10.0 7.02 10 7.02 10 +M -M“L”

Lead“R”

Lead

1.27 1.69 2.12 2.97 4.24 5.95 8.47 - 16.9 - 25.5 +.18 .06 0

1.30 1.74 2.17 3.05 4.35 6.10 8.70 12.2 17.4 - 26.1 +.15 .06 .03

1.34 1.79 2.23 3.13 4.46 6.26 8.93 12.5 17.9 - 26.8 +.12 .09 0

1.38 1.83 2.29 3.22 4.59 6.44 9.17 12.9 18.3 - 27.5 +.09 .09 .03

1.42 1.89 2.36 3.31 4.72 6.62 9.43 13.2 18.9 - 28.3 +.06 .06 .09

1.46 1.94 2.43 3.41 4.85 6.82 9.71 13.6 19.4 - 29.1 +.03 .03 0

1.50 2.0 2.50 3.51 5.00 7.02 10.0 14.0 20.0 - 30.0 0 0 0 0

1.55 2.06 2.58 3.62 5.15 7.24 10.3 14.5 20.6 - 30.9 -.03 0 .03

1.60 - 2.66 3.73 5.32 7.47 10.6 14.9 21.3 - 31.9 -.06 .09 .06

1.65 - 2.75 3.86 5.49 7.71 11.0 15.4 22.0 - 33.0 -.09 .03 .09

- - 2.84 3.99 5.68 7.98 11.4 16.0 22.7 23.9 34.1 -.12 0 .09

- - 2.94 4.13 5.88 8.26 11.8 16.5 23.5 24.8 35.3 -.15 .03 .06

the compensator loading resistors PF and PR.Refer to Repair Calibration when a change inmaximum sensitivity angle is desired.

6.0 INSTALLATIONThe relays should be mounted on switchboardpanels or their equivalent in a location free fromdir t, moisture, excessive vibration and heat.Mount the relay vertically by means of the fourmounting holes on the flange for the semi-flushtype FT case. Either the stud or the mountingscrews may be utilized for grounding the relay.The electrical connections may be made directlyto the terminals by means of screws for steelpanel mounting or to the terminal stud furnishedwith the relay for thick panel mounting. The ter-minal stud may be easily removed or inserted bylocking two nuts on the stud and then turning theproper nut with a wrench.

For detailed information on the FT case, refer toI.L. 41-076.

7.0 ACCEPTANCE TESTSKS-3 relays have a very small number of movingpar ts and mechan ica l dev ices wh ich m ightbecome inoperative. Acceptance tests in generalconsists of:

1. A visual inspection to make sure there are noloose connections, broken resistors, or bro-ken resistor wires.

2. An electrical test to make certain that therelay measures the balance point impedanceaccurately.

7.1 DISTANCE UNIT

1. Use the test connection shown in Figure 6.

Set TAF = TBF = 1 θMF = +15, which is equivalent to ZL = 8.7

ohmZL = 8.7 ohm

SF = 1

8

41-492.3A

Set TAR = TBR =2.03, which is equivalent to ZR =

2.03.

2. Adjust the relay voltage (across terminals 7 &8) for 60 volts A.C.

Set the relay current to lag the relay voltageby 75°.

The current required to operate the cylinderun i t (open ing o f i t s contac ts ) shou ld bebetween 3.10 - 3.80 amps ac.

Note, Itest = V/2Z.

Set the relay current to lag the relay voltageby 255°, and reduce the voltage to 30 Vac.

The current required to operate the cylinderunit (opening its contacts) should be between7-8 amps ac.

If the electrical response is outside the limits,a more complete series of tests outlined inthe section “Calibration” may be performed todetermine which component is faulty or out ofcalibration.

Check the time delay unit (telephone relay)by applying the rated dc voltage across termi-nals 18 and 20. Opening the cyl inder unitcontacts should cause the telephone typerelay to pick up. It should drop out when thecylinder unit contacts close. Check the direc-tion of Zener diodes between terminals 20and 1, and 20 and 6 using an ohmmeter toperform this test. The ohmmeter should havebattery as its energy source. Blocking shouldbe in direction from 20 to 1 and 6. Forwardconduction should be from 1 to 20, and from6 to 20.

8.0 ROUTINE MAINTENANCEAll relays should be inspected per iodical ly, atsuch time intervals as may be dictated by experi-ence, to insure that the relays have retained theircalibration and are in proper operating condition.

All contacts should be cleaned periodically. Acon t ac t bur n ishe r #182A836H01 i s recom-mended for this purpose. The use of abrasivemater ial for c leaning contacts is not recom-mended, because of the danger of embedding

small particles in the face of the soft silver andthus impairing the contact.

9.0 REPAIR CALIBRATIONUse the following procedure for cal ibrating therelay if the relay has been taken apart for repairsor the adjustments disturbed:

Auto-Transformer Check

Auto-transformers may be checked for turns ratioand polarity by using the test connections of Fig.5 and following the procedure outlined below.

Set SF on tap number 3. Set the “R” leads of MF

on 0.0 and disconnect the “L” lead. Adjust therelay voltage for 90 volts. Measure the voltagefrom terminal 8 to the #1 tap of SF. It should be

30 volts. From 8 to the #2 tap of SF should be 60

volts.

Set SF on 1 and adjust relay voltage for 1 0 0

volts. Measure the voltage drop from terminal 8to each of the MF taps. The voltage should be

equal to 100 (1 + the sum of values between Rand the tap being measured). Example- 100 (1+ .03 + .06) = 109 volts.

Transformers that have an output different fromnominal by more than 1.0 volt probably havebeen damaged.

Replace L-Lead.

Settings

Set TAF = TBF = 10

TAR = TBR = 2.03

MSF = 1

9.1 DISTANCE UNIT CALIBRATION

Initial Spring Adjustment

With the stationary contact open so that the mov-ing contact cannot touch, set the moving contactspring adjuster so that the contact floats freely inthe gap. Make sure that there is no friction whichprevents free movement of the cylinder and con-tact arm.

The upper pin bearing should be screwed downuntil there is approximately .025 inch (one com-plete turn of the screw) between it and the top ofthe shaft bearing. The upper pin bearing should

9

41-492.3A

then be securely locked in position with the locknut. The lower bearing position is fixed and can-not be adjusted.

9.2 CORE ADJUSTMENT

Apply 120 Vac to relay terminals. Adjust coreusing a screwdriver so that moving arm is float-ing in the gap, or restrains slightly.

9.3 COMPENSATOR ANGLE ADJUSTMENT

Use Figure 6 Test Connections.

Apply 20 Vac to relay terminals. Apply 1.15 ampac to relay current circuit lagging voltage by 75°.Connect high impedance voltmeter across CFcapacitor (0.7 uf) and adjust PF marked potenti-

ometer until voltage across this capacitor is mini-mum (below 0.5 volts). Readjust current slightlyto see if lower minimum voltage can be obtained.

Reconnect voltmeter to CR capacitor (1.6 ufd),

and apply 5 amp ac lagging voltage by 255° torelay terminals. Readjust P I until minimum volt-age read ings obta ined across CR capac i to r

(below 0.5 volts).

Readjust current slightly to see if lower minimumvoltage can be obtained.

Maximum Torque Sensitivity Angle

Apply 60 vo lts to relay ter minals. Set phaseshifter so that current of 4.25 amps ac just openscylinder unit contacts. Find another angle wherecontacts just open. The two points of cylinderunit operation (contact opening) should occur atthe two angles sum of which when, divided bytwo is equal to 75 ± 6 degrees. If not, readjustadjustable inductor. Sometimes the coils of theadjustable inductor can be reconnected from par-allel to series, or vice versa, connection to bringthe maximum sensitivity angle within the desiredrange of operation.

Adjustable inductor has a retaining nut which hasto be loosened before ad just ing core, and i tshould be retightened after adjustment is com-plete.

9.4 CONTACT ADJUSTMENT

With the moving contact arm against the left-hand side of the br idge, screw the right handcontact in to just touch the moving contact. Then

back the contact out one full turn to give approxi-mately 0.031 inch gap.

9.5 SPRING RESTRAINT

Apply 5 volts to relay terminal, set phase shifterfor 75 degree current of 0.350 amp ac lagging thevoltage.

Set the moving contact spring adjuster so thatthe contact just f loats. Deenergize relay com-pletely. The contacts should stay closed.

9.6 COMPENSATOR CHECK

Accuracy of the mutual impedance ZC of the

compensator is set within very close tolerancesat the factory and should not change under nor-mal conditions.

The mutual impedance of the compensators canbe checked with very accurate instruments by theprocedure below:

1. Disconnect S and L leads.

2. Apply 5 amps to relay.

Current only is applied to relay and voltage termi-nals (7 & 8) should be left open circuited. Com-pensator voltage should be equal to compensatortap setting multiplied by 2 times current.

The compensator voltage should be measuredfor forward reach compensator between lead “L”and either terminal of CF (0.7 mfd) capacitor or

VCF = 2IT , where I current applied, T com-

pensator tap setting, and angle θ, compensatorangle setting.

Example:

If T = 10 I = 5 amp θ75

VC = 100 volts

For reverse reach compensator voltage is mea-sured from terminal 7 to either terminal of 1.6mfd capacitors (CR).

Use the same equation, as above to calculatevoltage compensator (VC) = 20 volts.

Most accurate measurements should be donewith RR and RF resistors open, which will corre-

spond to θ = 90°, which will increase compensa-tor output.

θsin( )75sin

----------------

10

41-492.3A

Compensator which deviate by more than 3 per-cent with Phase Shifting resistor open circuitedshould be replaced, or accounted for in reachcalculations.

9.7 TELEPHONE RELAY

With the cyl inder unit contacts open, energizethe telephone relay through terminal 18 and 20wi th ra ted dc vo l tage and measure the t imerequired for the contacts to open between termi-na ls 4 and 5. Th is opera t ing t ime should bebetween three and four cycles, (50 and 66 milli-

seconds). The operating time can be adjusted bybending the contact-springs located at the topleft-hand side of the OS unit and by changing thearmature gap.

THE RELAY IS NOW CALIBRATED ANDREADY FOR SERVICE.

11

41-492.3A

12

Fig

ure

2.E

xter

nal C

onne

ctio

ns o

f KS

-3 R

elay

* D

enot

es

Ch

ange

* S

ub

41

60

3C

07

41-492.3A

13

Figure 3. Internal Schematic

Sub 13526A98

41-492.3A

14

Figure 4. Relay Characteristic on R-X Diagram

Sub 29642A98

41-492.3A

15

Figure 5. Compensator Construction

Sub 1849A034

41-492.3A

16

Fig

ure

6.Te

st D

raw

ing

of K

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ABB Inc.4300 Coral Ridge DriveCoral Springs, Florida 33065Telephone: +1 954-752-6700Fax: +1 954-345-5329www.abb.com/substation automation

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