Manual / Guide

Strowger selector operation diagrams — Sam Hallas repository (GPO-style teaching diagrams)

45 pp. Step-by-step pictures of a final selector and of a uniselector with a homing arc

Author: Sam Hallas repository (GPO-style teaching diagrams)
Type: Manual / Guide
Credit: Source: http://www.samhallas.co.uk/repository/documents/final_selector.pdf

Strowger selector operation diagrams – contents Ordinary final selector - idle state Final selector - moment of seizure Final selector - just after seizure Final selector - vertical stepping Final selector - end of vertical stepping Final selector - switch over to rotary Final selector - rotary stepping Final selector - end of rotary steps Subscriber’s uniselector with double homing arc Final selector - called line is free Final selector - ringing a free line Final selector - call answered Caller’s uniselector - lifting the handset Caller’s uniselector - hunting for free group selector Caller’s uniselector - free group selector found Caller’s uniselector - call established Caller’s uniselector - call terminates Subscriber’s uniselector with single homing arc Uniselector - incoming call Uniselector - P guarding during ringing Uniselector - caller lifts handset Uniselector - free 1st selector found Uniselector - connected Uniselector - end of call UAX13 group selector - idle state UAX13 group selector - moment of seizure UAX13 group selector - preparing for dial pulses UAX13 group selector - end of vertical stepping UAX13 group selector - free next selector found 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 UAX13 group selector - connecting to next selector Ordinary group selector 200 outlet Ordinary group selector - moment of seizure Ordinary group selector - vertical stepping Ordinary group selector - end of vertical stepping Ordinary group selector - first rotary step Ordinary group selector - free outlet found Ordinary group selector - connecting Ordinary group selector - normal release UAX13 group selector and ordinary final selector When group and final selector are both UAX13 UAX13 group selector - moment of connection UAX13 group selector - providing 150 Ohm battery UAX13 group selector - external relay activation UAX13 group selector - connection made 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 1 Ordinary final selector – idle state _ + A 200 200 CD2 B4 P wire A1 N3 B2 B N2 TO F, H AND J RELAYS 1300 MR2 CD1 METER PULSE CONNECTION HERE CD R2 200 E NR2 5 1500 F6 700 E5 B1 R3 1k2 ROTARY RELEASE CONNECTION CD4 E3 H5 NR1 RM VM E1//D1 2 Final selector – moment of seizure – A operates and removes short-circuit of B _ + A 200 200 CD2 B4 A1 P N3 B2 B N2 1300 MR2 CD1 CD R2 E NR2 5 1500 F6 700 E5 B1 CURRENT FLOW IN RED R3 CD4 E3 H5 NR1 RM VM E1 3 Final selector – just after seizure – A, B and CD operate _ + A CD2 200 200 B4 A1 P N3 B2 INCOMING PRIVATE WIRE EARTHED B N2 1300 MR2 CD1 CD R2 E NR2 5 1500 F6 700 E5 B1 R3 CD4 E3 H5 NR1 RM VM E1 4 Final selector – vertical stepping – A and VM are pulsing, B and CD are holding on short circuits _ + A CD2 200 200 B4 A1 P N3 B2 B N2 1300 shortcircuit MR2 CD1 CD R2 E NR2 5 1500 F6 700 E5 B1 R3 1k2 CD4 E3 H5 NR1 RM VM E1 5 Final selector – end of vertical stepping – A and B operate, CD releases, E slow to operate _ + A CD2 200 200 B4 A1 P N3 B2 B N2 1300 MR2 CD1 CD R2 E NR2 5 1500 F6 700 E5 B1 R3 CD4 E3 H5 NR1 RM VM E1 6 Final selector – switch over to rotary – A, B and E operate, CD re-operates _ + A CD2 200 200 B4 A1 P N3 B2 B N2 1300 MR2 CD1 CD R2 E NR2 5 1500 F6 700 E5 B1 short-circuit on CD removed R3 CD4 E3 H5 NR1 RM VM E1 7 Final selector – rotary stepping – A and RM pulsing, B and CD holding, E operates _ + A CD2 200 200 B4 A1 P N3 B2 B N2 1300 MR2 CD1 CD R2 E NR2 5 1500 F6 700 E5 B1 R3 1k2 CD4 E3 H5 NR1 RM VM E1 8 Final selector – end of rotary steps – A and B operate, CD and E release slowly, CD re-operates _ + A CD2 200 200 B4 A1 P N3 B2 B N2 1300 MR2 CD1 CD R2 E NR2 5 1500 F6 700 E5 B1 R3 CD4 E3 H5 NR1 RM VM E1 9 Subscriber’s uniselector with DOUBLE homing arc – idle state L2 M.D.F. K3 B3 MULT. P LOCAL P H -50V L1x CD3 K H 1300 K5 DMdm FINAL SELECTOR DM L 700 _ _ K1 H3 H4 LINE SIDE + M.D.F. K2 EXCH SIDE + SUBSCRIBER’S UNISELECTOR 10 Final selector – called line is free – CD releases, H (900 Ohm) and K operate, L is disconnected L2 M.D.F. K3 B3 900 MULT. P LOCAL P H L1x CD3 K H 1300 K5 DMdm FINAL SELECTOR (after last digit dialled) DM Ringing current in green L 700 _ _ K1 H3 PREPARED FOR RINGING H4 LINE SIDE CALLED PHONE + M.D.F. K2 EXCH SIDE + CALLED SUBSCRIBER’S UNISELECTOR IF NOT ENGAGED 11 Final selector – ringing a free line – E releases slowly, CD, J and H (on 400 Ohm winding) operate F7 H3 F8 _ H4 + A 200 570 200 F1 F2 R1 D H2 P CD4 J3 J1 E D1 F5 RING RTN BATTERY 1500 H1 HOLDING UNISELECTOR K RELAY F4x N2 VM RING TONE TO CALLER F 300 400 E4 B4 J 800 400 INT RING TO CALLED BELL 900 H B3 CD3 12 Final selector – call answered – CD, D, E and F operate, J releases (slowly) after meter pulse F7 H3 F8 VOICE CONNECTION _ H4 + A 200 570 200 F1 F2 R1 D H2 P CD4 J3 J1 E 1500 D1 F5 HOLDING UNISELECTOR K RELAY H1 F4x N2 VM RING TONE TO CALLER F 300 400 E4 B4 J 800 INT RING 400 900 H B3 CD3 13 Caller’s uniselector – lifting the handset – L operates slowly TO GROUP SELECTORS M.D.F. MULT. _ K1 LOCAL _ H3 K2 H4 + + L CALLER LINE SIDE 700 GUARDED GROUP SELECTORS EXCH SIDE L2 K3 P B3 P H L1x CD3 K H 1300 K5 DM MULTIPLE FINAL SELECTORS DMdm CALLER’S UNISELECTOR 14 Caller’s uniselector – hunting for free group selector - L operates, DM pulsing TO GROUP SELECTORS M.D.F. MULT. _ K1 LOCAL _ H3 K2 H4 + + L CALLER LINE SIDE 700 GUARDED GROUP SELECTORS EXCH SIDE L2 K3 B3 P P CD3 H H P WIRE MULTIPLE EARTHED VIA HOMING ARC HOME POSITION L1x K K5 DM MULTIPLE FINAL SELECTORS 1300 DMdm CALLER’S UNISELECTOR 15 Caller’s uniselector – free group selector found – K operates, L releases slowly M.D.F. MULT. _ K1 LOCAL _ LOOP CURRENT FROM GROUP SELECTOR H3 K2 H4 + + L CALLER LINE SIDE 700 GUARDED GROUP SELECTORS EXCH SIDE L2 K3 B3 P P CD3 H H P WIRE MULTIPLE EARTHED VIA HOMING ARC L1x K L2 AND K3 PROVIDE TEMPORARY EARTH TO SEIZED SELECTOR 1300 K5 DM MULTIPLE FINAL SELECTORS DMdm CALLER’S UNISELECTOR 16 Caller’s uniselector – call established – K held by group selector P wire M.D.F. MULT. _ K1 LOCAL _ LOOP CURRENT FROM GROUP SELECTOR H3 K2 H4 + + L CALLER LINE SIDE 700 EXCH SIDE L2 K3 B3 P P CD3 H H P WIRE MULTIPLE EARTHED VIA HOMING ARC L1x K SEIZED SELECTOR RETURNS EARTH 1300 K5 DM MULTIPLE FINAL SELECTORS DMdm CALLER’S UNISELECTOR 17 Caller’s uniselector - call terminates - no loop current – K releases – DM steps home M.D.F. MULT. _ K1 LOCAL _ H3 K2 H4 + + L CALLER LINE SIDE 700 EXCH SIDE L2 K3 P B3 P CD3 H H P WIRE MULTIPLE EARTHED VIA HOMING ARC L1x K 1300 K5 DM MULTIPLE FINAL SELECTORS DMdm CALLER’S UNISELECTOR 18 Subscriber’s uniselector with SINGLE homing arc - idle state - H, K and L not operating L2 M.D.F. K3 P MULT. LOCAL P - 50V L1 400 900 B3 CD3 K H 1300 DMdm K5 H FINAL SELECTOR DM L 700 _ _ K1 H3 H4 LINE SIDE BELL LOOP + M.D.F. K2 EXCH SIDE + SUBSCRIBER’S UNISELECTOR 19 Uniselector – incoming call – H (900) operates on brief CD release, K operates, L releases L2 M.D.F. K3 P B3 900 MULT. LOCAL P L1 CD3 K H 1300 DMdm K5 H FINAL SELECTOR (last digit dialled) DM L 700 _ _ K1 H3 PREPARED FOR RINGING H4 LINE SIDE BELL LOOP + M.D.F. K2 EXCH SIDE + CALLED SUBSCRIBER’S UNISELECTOR IF NOT ENGAGED 20 Uniselector– P guarding during ringing – CD operates again, H(400) takes over from H(900) L2 M.D.F. K3 H2 P B3 900 400 CD3 MULT. LOCAL P L1 K H 1300 DMdm K5 H FINAL SELECTOR DM L 700 _ _ K1 H3 PREPARED FOR RINGING H4 LINE SIDE BELL LOOP + M.D.F. K2 EXCH SIDE + CALLED SUBSCRIBER’S UNISELECTOR IF NOT ENGAGED 21 Uniselector – caller lifts handset – L operates on caller loop, DM steps on DMdm L2 M.D.F. K3 P MULT. LOCAL P L1 400 900 B3 CD3 K H DMdm 1300 K5 H FINAL SELECTOR DM L 700 _ _ K1 H3 H4 LINE SIDE CALLER LOOP + M.D.F. K2 EXCH SIDE + CALLING SUBSCRIBER’S UNISELECTOR 22 Uniselector – free 1st selector found – K operates, L releases slowly FREE 1st SELECTOR L2 M.D.F. K3 P MULT. LOCAL P L1 400 900 B3 CD3 K H DMdm 1300 K5 H FINAL SELECTOR DM L 700 _ K1 H3 H4 LINE SIDE CALLER LOOP _ 1st SELECTOR LOOP + M.D.F. K2 EXCH SIDE + CALLING SUBSCRIBER’S UNISELECTOR 23 Uniselector – connected – K operates on 1st selector earth L2 M.D.F. K3 P MULT. FREE 1st SELECTOR EARTH RETURNED LOCAL P L1 400 900 B3 CD3 K H DMdm 1300 K5 H FINAL SELECTOR DM L 700 _ K1 H3 H4 LINE SIDE CALLER LOOP _ 1st SELECTOR LOOP + M.D.F. K2 EXCH SIDE + CALLING SUBSCRIBER’S UNISELECTOR 24 Uniselector – end of call – P earth removed, K releases, DM steps home L2 M.D.F. K3 P MULT. FREE 1st SELECTOR EARTH REMOVED LOCAL P L1 400 900 B3 CD3 K H DMdm 1300 K5 H FINAL SELECTOR DM L 700 _ K1 H3 H4 LINE SIDE OPEN LOOP + M.D.F. K2 EXCH SIDE _ + CALLING SUBSCRIBER’S UNISELECTOR 25 UAX13 group selector – idle state _ _ H5 H6 + CC1 H7 + A 200 M 200 C2 570 BUSY TONE EARTH CC5 DIAL TONE EARTH M S3 N.U. TONE EARTH INT BATT & EARTH MRA P S2 P H1 (AT BATT LEVEL) S1 CC2 VMB CBO H YC 2k HX 2000 2000 11 B2 NR1 TM1 A1 B5 B1 2000 CC B3 N3 CB N2 TP RELEASE H4 CC4 B C3 N1 HX1 YA 150 H3 B4 1300 RELEASE RELAY YB 500 C1 CC3 H2 TM R1 C 1000 1000 QA RM RELEASE ALARM EARTH 3 VM 200 TM2 TP START TP HOLD 26 UAX13 group selector – moment of seizure – A and B operate _ _ H5 H6 + CC1 H7 + A 200 M 200 C2 570 BUSY TONE EARTH CC5 DIAL TONE EARTH M S3 N.U. TONE EARTH INT BATT & EARTH MRA P S2 P H1 (AT EARTH LEVEL) S1 CC2 VMB CBO H YC 2k HX 2000 2000 11 B2 NR1 TM1 A1 B5 B1 2000 CC B3 N3 CB N2 TP RELEASE H4 CC4 B C3 N1 HX1 YA 150 H3 B4 1300 RELEASE RELAY YB 500 C1 CC3 H2 TM R1 C 1000 1000 QA RM RELEASE ALARM EARTH 3 VM 200 TM2 TP START TP HOLD 27 UAX13 group selector – preparing for dial pulses – C and CC operate _ _ H5 H6 + CC1 H7 + A 200 M 200 C2 570 BUSY TONE EARTH CC5 DIAL TONE EARTH M S3 N.U. TONE EARTH INT BATT & EARTH MRA S2 P H1 P S1 CC2 VMB CBO H YC 2k HX 2000 2000 11 B2 NR1 TM1 A1 B5 B1 2000 CC B3 N3 CB N2 TP RELEASE H4 CC4 B C3 N1 HX1 YA 150 H3 B4 1300 RELEASE RELAY YB 500 C1 CC3 H2 TM R1 C 1000 1000 QA RM RELEASE ALARM EARTH 3 VM 200 TM2 TP START TP HOLD 28 UAX13 group selector – end of vertical stepping – C, CC release, hunting for free outlet _ _ E.G. NR 3 IS FREE H5 H6 + CC1 H7 + A 200 M 200 C2 570 BUSY TONE EARTH CC5 DIAL TONE EARTH M S3 N.U. TONE EARTH INT BATT & EARTH MRA S2 P H1 P S1 CC2 VMB CBO H YC 2k HX 2000 11 B2 NR1 CB 2000 TM1 A1 B5 B1 2000 CC B3 N3 E.G. DIALLED 6 N2 TP RELEASE H4 CC4 B C3 N1 HX1 YA 150 H3 B4 1300 RELEASE RELAY YB 500 C1 CC3 H2 TM R1 C 1000 1000 QA RM RELEASE ALARM EARTH 3 VM 200 TM2 TP START TP HOLD 29 UAX13 group selector – free next selector found – HX operates on P wire battery(!) _ _ E.G. NR 3 IS FREE H5 H6 + CC1 H7 + A 200 M 200 C2 570 BUSY TONE EARTH CC5 DIAL TONE EARTH M S3 N.U. TONE EARTH INT BATT & EARTH MRA P wire on batt !! S2 P H1 P S1 CC2 VMB CBO H YC 2k HX 2000 11 B2 NR1 CB 2000 TM1 A1 B5 B1 2000 CC B3 N3 E.G. DIALLED 6 N2 TP RELEASE H4 CC4 B C3 N1 HX1 YA 150 H3 B4 1300 RELEASE RELAY YB 500 C1 CC3 H2 TM R1 C 1000 1000 QA RM RELEASE ALARM EARTH 3 VM 200 TM2 TP START TP HOLD 30 UAX13 group selector – connecting to next selector – H operates, HX, A and B release _ _ E.G. NR 3 IS FREE H5 H6 + CC1 H7 + A 200 M 200 C2 570 BUSY TONE EARTH CC5 DIAL TONE EARTH M S3 N.U. TONE EARTH INT BATT & EARTH MRA P wire earthed S2 P H1 P S1 CC2 VMB CBO H YC 2k HX 2000 11 B2 NR1 CB 2000 TM1 A1 B5 B1 2000 CC B3 N3 E.G. DIALLED 6 N2 TP RELEASE H4 CC4 B C3 N1 HX1 YA 150 B4 H3 1300 RELEASE RELAY YB 500 C1 CC3 H2 TM R1 C 1000 1000 QA RM RELEASE ALARM EARTH 3 VM 200 TM2 TP START TP HOLD 31 Ordinary group selector 200 outlet – idle state _ _ NR2 + HA5 CD5 BUSY TONE EARTH 200 570 200 A HA2 + S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 P1 HA1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 32 Ordinary group selector – moment of seizure – A, B and CD operate _ _ NR2 + HA5 CD5 BUSY TONE EARTH 200 570 200 A HA2 + S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 P1 HA1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 33 Ordinary group selector – vertical stepping – N1, N2, HA and HB (750 Ohm) operate _ _ NR2 + HA5 CD5 BUSY TONE EARTH 200 570 200 A HA2 + S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 P1 HA1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 34 Ordinary group selector – end of vertical stepping – CD releases slowly, RM operates _ _ NR2 + HA5 CD5 BUSY TONE EARTH 200 570 200 A HA2 + S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 P1 HA1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 35 Ordinary group selector – first rotary step – RM1 breaks RM and HA/HB (750) circuits _ _ NR2 + HA5 CD5 BUSY TONE EARTH 200 570 200 A HA2 + S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 P1 HA1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD ASSUME BOTH P1 AND P2 EARTHED ON FIRST OUTLET: HA AND HB HOLD ON 400 OHM COIL 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 36 Ordinary group selector – free outlet found – HA and HB release, CD re-operates _ _ NR2 + CD5 HA5 BUSY TONE EARTH 200 570 200 A HA2 + S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 HA1 P1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD ASSUME BOTH P1 AND P2 ARE FREE ON SECOND OUTLET 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 37 Ordinary group selector – connecting – A and B release, HA operates on 1500 Ohm coil _ _ NR2 + CD5 HA5 BUSY TONE EARTH 200 570 200 A + HA2 S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 HA1 P1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD HA HOLDING ON P WIRE EARTH OF SUCCEEDING SELECTOR 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 38 Ordinary group selector – normal release – HA and CD release, RM steps home _ _ NR2 + CD5 HA5 BUSY TONE EARTH 200 570 200 A + HA2 S1 B6 B4 DIAL TONE EARTH NR3 HB6 CD6 HA1 P1 B3 P S2 HB5 HB1 _ HA4 HB RM1 N1 B5 1500 750 400 + CD4 NR1 CD2 B7 RLSE ALM EARTH HB7 HB3 HA7 HA6 HA3 HB2 P2 R1 800 B2 LP1 700 CD HA RELEASES ON FREEING OF P WIRE OF SUCCEEDING SELECTOR 5 VM R4 300 C1 R3 500 CD1 CD3 R2 200 B N2 RM A1 1300 NR4 B1 1500 750 400 HA 39 UAX13 Group Selector connected to an Ordinary Final Selector (Example: ATW 600670 connected to ATW 52160) to Final Selector P P H7 U9 S1 H 2000 2000 U25 B3 HX 11 N2 NR1 B5 N3 U10 150 HX1 H6 A UAX13 GROUP SELECTOR EXPECTS A 150 OHM BATTERY ON THE P WIRE OF A FREE FINAL SELECTOR TO OPERATE RELAY HX. A FREE ORDINARY FINAL SELECTOR DOES NOT PROVIDE POWER ON ITS INCOMING P WIRE RM 40 When group selector and final selector are both UAX13 – HX operates on 150 Ohm P wire battery P wire on batt !! P P H7 U9 S1 H 2000 2000 U25 B3 HX 11 N2 NR1 B5 N3 U10 150 HX1 H6 CURRENT FLOW SHOWN IN RED, JUST AFTER HX OPERATES ON P WIRE BATTERY H CONTACTS NOT YET ACTIVATED RM 41 UAX13 group selector – connecting to next selector – H operates, B and HX release P wire gets earthed P P H7 U9 S1 H U25 2000 2000 B3 HX 11 N2 NR1 B5 N3 U10 150 HX1 H6 B RELEASES, P WIRE IS EARTHED BY NEXT SELECTOR H6 TAKES OVER FROM HX1 RM 42 Providing 150 Ohm battery to Final Selector P P HY1 H7 U9 S1 HY H 2000 2000 U25 B3 HX 11 47uF 160V N2 NR1 B5 N3 U10 150 HX1 RM H6 TEMPORARY BATTERY CAN BE ARRANGED BY CONNECTING AN ADDITIONAL RELAY HY BETWEEN POINTS U9 AND U10. RELAY B (NOT SHOWN HERE) OPERATES WHEN THE GROUP SELECTOR IS SEIZED. IT PUTS AN EARTH TO U9. A 150 OHM BATTERY IS ALREADY AVAILABLE ON POINT U25. HY1 CONNECTS THE BATTERY TO THE P BANK. THE EXTERNAL RELAY IS ACTIVATED WHEN HX OPERATES ON TESTING A FREE FINAL SELECTOR. THAT DISCONNECTS THE BATTERY FROM THE P WIRE. BY THAT TIME THE FREE FINAL SELECTOR IS SEIZED. A CAPACITOR HAS BEEN ADDED TO DELAY THE SEQUENCE. A RELAY WITH A SLUG MAY ALSO BE USED. 43 UAX13 group selector – additional external relay HY to provide temporary batt on P wire P wire on batt !! P P HY1 H7 U9 S1 H HY 2000 2000 U25 B3 HX 11 47uF 160V N2 NR1 B5 N3 U10 150 HX1 H6 CURRENT FLOW SHOWN IN RED, JUST AFTER HX OPERATES ON P WIRE BATTERY H CONTACTS AND HY1 NOT YET ACTIVATED RM RELAY HY: SONGLE SRD-48VDC-SL-C ADDED 47uF CAPACITOR TO CONTACTS TO SLOW THE RESPONSE 44 UAX13 group selector – connecting to ordinary selector – H and HY operate, B and HX release P wire gets earthed P P HY1 H7 U9 S1 H HY U25 2000 2000 B3 HX 11 47uF 160V N2 NR1 B5 N3 U10 150 HX1 H6 CURRENT FLOW SHOWN IN RED, JUST AFTER H OPERATES B RELEASES, P WIRE EARTED BY NEXT SELECTOR H6 TAKES OVER FROM HX1 RM 45