S&C Source-Transfer ControlsI

In Weatherproof EnclosuresType AT-2

INSTRUCTIONSFor Installation & Operation

1 TABLE OF CONTENTS I

Section Page NumberINTRODUCTION .......................................1FUNCTIONAL PERFORMANCE ........................4INSTALLATION....................................... .6ADJUSTMENTS AND PROGRAMMING ................6

Section Page NumberOPERATIONAL TESTING ............................. .8OPERATION ......................................... ..lOMAINTENANCE..................................... ..13SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..I 4

1 INTRODUCTION I

CAUTION: The equipment covered by this publicationmust be operated and maintained by qualified personswho are thoroughly trained and who understand anyhazards that may be Involved. This publication is writtenonly for such qualified persons and is not intended tobe a substitute for adequate training and experience insafety procedures for this type of equipment.

GeneralThe following instructions are for field installation andoperation of S&C Source-Transfer Controls-TypeAT-2 in Weatherproof Enclosures. See Figure 1. Thesecontrols are designed for use in conjunction with pole-mounted or steel-structure-mounted S&C Alduti-Rupter@ Switches that are power-operated by S&CSwitch Operators-Type AS-1A (for rotating operatingmechanisms) or Type AS-10 (for reciprocating oper-ating mechanisms) equipped for this application. Thisarrangement provides automatic source transfer forgrounded primary-selective overhead distributionsystems rated 7.2 kv through 46 kv.

For installation and operation instructions for theAlduti-Rupter Switches and switch operators, refer tothe specific S&C instruction sheets furnished withthose devices.

Figure 1. S&C Type AT-2 Source-Transfer Control inWeatherproof Enclosure.

Supersedes Instruction Sheet 514-510 dated 4-25-88 0 1988

INSTRUCTION SHEET 514-510S&C ELECTRIC COMPANY- Chicago Page 1 of 15S&C ELECTRIC CANADA LTD.-Toronto November 7,1988

S&C Source-Transfer Controls In Weatherproof Enclosures Type AT-2 I I INTRODUCTION - Continued I

Features Test switches to simulate loss of source (as well as S&C Source-Transfer Controls-Type AT-2 In Wea- overcurrent when the optional overcurrent-lockout therproof Enclosures include the following standard feature has been specified). features illustrated in Figure 2: Provisions for field selection of preferred and alter- * ManuaYautomatic operation selector switch. nate sources.

Selector switch for automatic return mode or hold return mode. Selector switch for open transition (nonparalleling) or closed transition (paralleling) on retransfer. Automatic-transfer “ready” indicating lamp and source-voltage indicating lamps. (All lamps have push-to-test feature.) Loss-of-source timer dials, field-adjustable from 1 to 30 seconds? or (by means of a 10-times selector switch) 10 to 300 seconds. Return-of-source timer dial, field-adjustable from !h to 15 minu ted Factory-adjusted for 5 seconds. Factory-adjusted for 3 minutes.

Voltage-seeking relay which transfers between the alternate source and preferred source, as required, to ensure adequate control voltage for the switch operators. Terminal strip for external connections. All necessary internal connections are prewired.

Fuseholders for secondary fuses of customer- furnished voltage transformers. Auxiliary transformers (only on source-transfer control using three-phase voltage sensing by means of two customer-furnished voltage transformers). Weatherproof padlockable enclosure.

5 1 4-5 1 0 INSTRUCTION SHEET Page 2 of 15 S&C ELECTRIC COMPANY Chicago November 7,1988 S&C ELECTRIC CANADA LTD: Toronto

INTRODUCTION - Continued I

Loss-of-Source Timer Adjustment DialsTime Range Selector Switch

Test Jacks for measusignal-voltage outputtransformers

Return-of-Source Timer Adjustment Dial

Overcurrent-Lockout-Reset Timer

Overcurrent-Lockout LevelDetector Switch (included withoptional overcurrent-lockout feature)

Pushbutton Test Switches tosimulate loss of source voltage

Automatic-Return/Hold-ReturnSelector Switch

Open-Transition-Return/Ciosed-Transition-Return Selector Switch

Manual/Automatic OperationSelector Switch

Overcurrent-Lockout indicatingLamp and Reset Pushbutton(included with optionalovercurrent-lockout feature)

Preferred-Source-Voltage andAlternate-Source-Voltageindicating Lamps

Grounding Connector

Automatic-Transfer “Ready”

\indicating Lamp

rusenoraers ror 3rgner-Voltage and GroundingCircuits (typical)

Voltage-Seeking Relay ensuresadequate control voltage forswitch operators

Terminal Strips for externalconnections

\Open-Phase Detection SelectorSwitch (included with optionalopen-phase detection feature)

Preferred-Source and Aiternate-Source Receptacles-connector plugsare interchangeable to allowselection of either source aspreferred

Figure 2. Closeup of adjustment, testing, and programming features.

INSTRUCTION SHEET 514151 0S&C ELECTRIC COMPANV~ Chicago Page 3 of 15

S&C ELECTRIC CANADA LTD.-Toronto November 7,1988

SBC Source-Transfer Controls In Weatherproof Enclosures Type AT-2 I I FUNCTIONAL PERFORMANCE 1 The Type AT-2 Source-Transfer Control assures a high degree of critical-load service continuity for primary- selective overhead distribution systems by minimizing interruptions resulting from loss of one source. Exclud- ing the intentional time delay to coordinate with upstream protective devices, transfer is achieved in 1.5 seconds maximum (when Type AS-1A Switch Operators are used) or 2.4 seconds maximum (when Type AS-10 Switch Operators are used).

Under normal operating conditions in a common-bus primary-selective system, the preferred-source interrupter switch is closed and the alternate-source interrupter switch is open. See Figure 3.

The Type AT-2 Source-Transfer Control monitors the condition of both power sources and initiates automatic switching when preferred-source voltage has been lost (or reduced below a predetermined level) for a period of time sufficient to confirm that the loss is not transient. The preferred-source interrupter switch is automatically opened and the alternate-source interrupter switch is then automatically closed, restor- ing power to the load.

Retransfer to the normal circuit configuration- preferred-source interrupter switch closed, alternate- source interrupter switch open-may be performed automatically on restoration of normal voltage to the preferred source, after a delay sufficient to establish that the return is not temporary (automatic return mode) or manually at a convenient time (hold return mode). In the automatic return mode, retransfer may be accom-

plished with open transition or closed transition. With open transition retransfer-used when the power sources are not to be paralleled-the alternate-source interrupter switch opens before the preferred-source interrupter switch closes . . . with a momentary interruption of service to the load. With closed transition retransfer-selected when it is permissible to parallel the sources so that there will be no interruption of service to the load-the alternate-source interrupter switch opens after the preferred-source interrupter switch closes. In the hold return mode, if the alternate source voltage fails (and voltage has been restored to the preferred source), an automatic open-transition retransfer will take place so that the load is served from the preferred source.

The voltage-sensing input circuitry of the source- transfer control can accommodate the following single- phase or three-phase sensing schemes, using customer- furnished voltage transformers having 240/120-volt, 60-hertz secondaries:

For single-phase sensing, one voltage transformer is required for each source, connected line-to-line or line-to-ground. For three-phase sensing, two line-to-line-connected voltage transformers are required for each source; a 1:l auxiliary transformer for each source is supplied by S&C when this sensing scheme is specified, to produce a third signal-voltage input. Alternately, three voltage transformers may be used for each source, connected line-to-ground.

S&C

Load

Preferred Source Alternate Source

a

I

I +I5 I I

T T‘Voltage Transformer

Alduti-Rupter Switch “D I I

S&C Source-Transfer Control-Type AT-2 In Weatherproof Enclosure

S&C Type AS-1 A or Type AS-10 Switch Operator

Figure 3. System diagram.

5 1 4-5 1 0 INSTRUCTION SHEET Page 4 of 15 S&C ELECTRIC COMPANY Chicago November 7,1988 S&G ELECTRIC CANADA LTD.. Toronto

I FUNCTIONAL PERFORMANCE - Continued 1 For three-phase sensing when the optional open- phase detection feature is specified, three voltage transformers are required for each source, connected line-to-ground. Voltage-transformer secondary fuses are contained

within the source-transfer control enclosure.

Open-Phase Detection S&C’s unique open-phase detection feature may be included on grounded-system applications to protect the load from any source-side open-phase condi- tion-whether caused by utility-line burndown, broken conductors, single-phase switching, equipment mal- functions, or single-phasing resulting from blown source-side fuses. This optional feature continuously develops and monitors the phasor sum of the line-to- ground voltages to detect any unbalance present as the result of an open-phase condition. If unbalance exceeds a preset reference level of 15% for a period of time sufficient to confirm that the loss is not transient, an output signal is produced which initiates automatic transfer to the other source. By summing phasor voltages, the S&C open-phase detection feature detects all source-side open-phase conditions, even those where backfeed defeats simple voltage-magnitude sensing schemes.

Overcurrent Lockout An overcurrent-lockout feature may also be included to prevent an automatic transfer operation that would close a source interrupter switch into a fault, thereby

avoiding further utility-system disturbance. When an overcurrent is due to a fault that is cleared by a source- side protective device, the prolonged loss of voltage causes the associated source interrupter switch to open. J4t the same time, a lockout mode is set up in the source- transfer control, so that the other source switch will not automatically close into the fault. (When overcur- rent is due to a fault that is cleared by a load-side ]protective device, there is no prolonged loss of voltage ;and hence the source-transfer control does not initiate ;any switching operations.)

When the overcurrent-lockout feature has been specified, three customer-furnished current-sensing devices are required for each source. Either current transformers or Fisher Pierce Series 1301 Powerflex@ Line Post Current Sensors may be used.

When current transformers are used, the overcurrent relay is factory-set to respond to a secondary current of 5 amperes or greater; the current-transformer ratio should be selected accordingly and should take into account the anticipated emergency peak-load current of the system, so as to preclude nuisance lockouts. When Fisher Pierce Series 1301 Powerflex Line Post Current Sensors are used, the overcurrent level detector is furnished with a four-position selector switch which permits field adjustment of the detection level for overcurrents in excess of 200 amperes, 400 amperes, 600 amperes, or 1200 amperes; in this instance, the selector switch setting should take into account the anticipated emergency peak-load current of the system, so as to preclude nuisance lockouts.

INSTRUCTION SHEET 5 1 4 4 1 0 S&C ELECTRIC COMPANY Chicago Page 5 of 15 S&C ELECTRIC CANADA LTD: Toronto November 7,1988

S8C Source-Transfer Controls In Weatherproof Enclosures Type AT12 I I INSTALLATION I

Step 1 Install the S&C Alduti-Rupter Switches and Type AS-1A or Type AS-10 Switch Operators in accordance with the S&C instruction sheets and erection drawing furnished with these devices. Also install the voltage transformers and, if the overcurrent-lockout feature (catalog number suffix “-K1” or “-K2”) has been specified, the current-sensing devices in accordance with the instructions provided by the suppliers of those devices.

Step 2 Attach the Type AT-2 Source-Transfer Control enclo- sure onto its mounting structure. Alternately, if the enclosure is to be pole-mounted, first attach the pole mounting bracket (catalog number suffix “-P”) onto the pole; then attach the enclosure to the mounting bracket.

Step 3 Attach the grounding connector on the enclosure to a suitable earth ground.*

Step 4 Remove the voltage-transformer secondary fuses and grounding circuit slugs from the source-transfer control.

Step 5 Complete the interconnections between the source- transfer control, the switch operators, the voltage transformers, and the current-sensing devices (as appropriate), in accordance with the system wiring diagram and the interconnection wiring diagram furnished with the source-transfer control. Then replace the fuses and slugs removed in Step 4.

operating and safety procedures of certain electric utility companies. * The grounding recommendations herein may differ from the standard

Where a discrepancy exlsts, the operating procedures of the electric utllity apply.

ADJUSTMENTS AND PROGRAMMING i The instructions which follow presuppose that the interrupter switches, switch operators, and source- transfer control have been installed in accordance with the applicable drawings, instruction sheets, and wiring diagrams, and that the equipment is in all respects ready for operation, with the high-voltage circuits energized.

Before proceeding, place the manual/automatic operation selector switch on the Type AT-2 control in the manual position and decouple the switch operators.

Timer Adjustments The loss-of-source timers“62P and 62A, the return- of-source timer”2P, and the overcurrent-lockout-reset timer-62LR (furnished when the optional overcur- rent-lockout feature, catalog number suffix “-K1” or “-K2,” has been specified) have all been factory-set and will maintain repetitive accuracy of +3% of their settings. Refer to the “SPECIFICATIONS” section on page 14 for their respective settings.

5 1 4-5 1 0 INSTRUCTION SHEET Page 6 of 15 November 7,1988

~

S&C ELECTRIC COMPANY. Chicago S&C ELECTRIC CANADA LTD: Toronto

These timers may be set, by means of their adjustment dials, to within +20% of a desired time delay. (For more precise settings, operational timing must be performed, with the manual/automatic operation selector switch in the automatic position; such tests should be performed upon completion of the instructions in this section. See “OPERATIONAL TESTING” on page 8.)

If other than the factory-set time delays are desired, perform Steps 6 through 8, as appropriate. Otherwise, proceed to Step 9.

Step 6 Adjust the 1-30 second loss-of-source timers for the preferred and alternate sources for the desired time delays. These timers may be optionally set for time delays in the range of 10-300 seconds by means of the l0-times selector switch.

The loss-of-source timers must be set to initiate opening of the source interrupter switch anZy after a

I ADJUSTMENTS AND PROGRAMMING - Continued I

time delay sufficient to allow the source-side circuit breaker to make the desired number of reclosure attempts-verifying that the loss of voltage is not transient. In any case, the time-delay setting must be longer than the longest total clearing time of any of the load-side feeder fuses at the anticipated fault-current lev- els-including those which could result from transformer secondary-side faults.

Step 7 Adjust the E-15 minute return-of-source timer for the period considered sufficient to establish that return of preferred-source voltage is not temporary.

Step 8 Adjust the 1-30 second overcurrent-lockout-reset timer, if furnished, for the time delay desired before the lockout circuit automatically resets. (This circuit is “set up” by an overcurrent of sufficient magnitude.)

The overcurrent-lockout-reset timer should be set for the period of time considered sufficient to establish that the return of source voltage is not temporary, as determined by the reclosing sequence of the source-side circuit breaker. (An overcurrent due to a load-side fault that is cleared by feeder fuses would be transient-no switching would occur and the timer would complete its cycle to reset the lockout circuit. An overcurrent due to a load-side fault not cleared by feeder fuses would result in a prolonged loss of source voltage-the affected source interrupter switch would open and the other source interrupter switch would remain open and locked out . . . the timer would not time out and lockout would remain in effect.)

Preferred-Source Selection Step 9

Select the preferred source by plugging the appropriate connecting plug into the L L p r e f e r r e d - ~ ~ ~ r ~ e ’ 7 receptacle on the Type AT-2 control. Plug the other connecting plug into the “alternate-~ource~~ receptacle.

Operating-Mode Selection Step 10

Place the automatic-returdhold-return selector switch im the desired mode. In “automatic-return,” retransfer tlo the normal circuit configuration-preferred-source interrupter switch closed, alternate-source interrupter switch open-will be performed automatically on restoration of normal voltage to the preferred source, after the period selected on the return-of-source timer. In “h~ ld - re tu rn ,~~ r e t r ans fe r mus t be performed manually-unless the alternate-source voltage becomes inadequate (and preferred-source voltage is adequate), in which case an automatic open-transition retransfer to the preferred source will take place.

Step 11 Place the open-transition-returdclosed-transition- return selector switch in the desired mode. In “open- transition-return,” automatic retransfer (if selected in Step 10) will result in the alternate-source interrupter :switch opening before the preferred-source interrupter switch closes-with a momentary interruption of service to the load. In “closed-transition-return,” automatic retransfer (if selected in Step 10) will result in the alternate-source interrupter switch opening after the preferred-source interrupter switch closes-so that there is no interruption of service to the load. “Closed- transition-return” should be selected only if paralleling of the sources is permissible.

Step 12 Place the open-phase detection selector switch, if furnished, in the “on” position.

Step 13 Set the overcurrent-lockout feature level-detector switch, if furnished, for the desired pickup level-200, 400,600, or 1200 amperes.

INSTRUCTION SHEET 5 1 4 4 1 0 S&C ELECTRIC COMPANY Chicago Page 7 of 15 S&C ELECTRIC CANADA LTD.-Toronto November 7,1988

s&C Source-Transfer Controls In Weatherproof Enclosures Type AT-2 I

OPERATIONAL TESTING I The operational testing procedures described herein should be performed during initial startup and then thereafter about once per year to verify that the source- transfer control and its associated switch operators are operational.

Since S&C Switch Operators-Type AS-1A and Type AS-10 may be readily decoupled from the associated Alduti-Rupter Switches, checkout of the functional performance (e.g., operating sequence and timing) of the Type AT-2 control-and the switch operators-may be accomplished at any convenient time, without requiring an interruption of service. Refer to “Timer Adjustments” on page 6.

Before proceeding, make sure that each switch operator is decoupled from its interrupter switch (unless temporary service interruptions are permissible) and that the manual/automatic operation selector switch on the Type AT-2 control is in the automatic position. The control will not function automatically if one switch operator is coupled and the other switch operator is decoupled.

As a point of information, when operational testing is performed with the switch operators decoupled, the “ready” indicating lamp will not light. (See “Conditions required to light ‘ready’ indicator lamp” on page 9.)

Loss-of-Source Testing Pushbutton test switches, for simulating loss of voltage on either the preferred or alternate source, are provided on the Type AT-2 control.

Simulate a loss of source voltage by pressing the preferred-source test pushbutton and holding it in that position long enough for the preferred-source loss-of- source timer to complete its preset cycle and for transfer to the alternate source to be complete. Then release the pushbutton, simulating a return of source voltage.

If the automatic-returdhold-return selector switch is programmed for automatic return, retransfer to the preferred source will take place automatically after a time period equal to the setting of the return-of-source timer. Retransfer will be closed transition or open transition as determined by the position of the open- transition-returnlclosed-transition-return selector switch.

On the other hand, if the automatic-returdhold- return selector switch is programmed for hold return (for manual return at a convenient time), no automatic retransfer will occur unless the alternate-source test pushbutton is then pressed and held in that position long enough for the loss-of-source timer for the alternate source to complete its cycle, in which case an automatic open-transition retransfer to the preferred source will take place. Otherwise, a manual retransfer to the preferred source may be accomplished in either of two ways: (1) Place the manual/automatic operation selector

switch on the Type AT-2 control in the manual position to prevent automatic operation. Each associated interrupter switch* may then be individ- ually opened and closed to accomplish the retransfer (in any sequence) by means of the appropriate “Open” or “Close” pushbutton located on the switch operator. Then place the manuallautomatic operation selector switch in the automatic position.

(2) Temporarily place the automatic-returdhold- return selector switch on the Type AT-2 control in the automatic return position. After retransfer to the preferred source has occurred, the automatic- return/hold-return selector switch may again be placed in the hold return position.

Overcurrent Lockout Testing If the optional overcurrent-lockout feature is furnished, pushbutton test switches for simulation of overcurrent conditions are provided on the AT-2 control. These pushbuttons-one for the preferred source and one for the alternate source-are positioned directly below the corresponding loss-of-source test pushbuttons.

To simulate an overcurrent, momentarily press, then release the simulate-overcurrent pushbutton for the source serving the load (simulating a fault that is cleared by feeder fuses). This will “set up” the lockout circuit, as indicated by illumination of the overcurrent-lockout indicating lamp on the Type AT-2 contol. However, the continuity of source voltage will start the overcur- rent-lockout reset timer which, after completing its

and closing operations, actually, if the switch operators are in the * Although the term “interrupter switch” is used in referring to openlng

and switch-closed positions. decoupled condltion, only the operators will move to their switch-open

5 1 4=5 1 0 INSTRUCTION SHEET Page 8 of 15 S&C ELECTRIC COMPANY Chicago November 7,1988 S&C ELECTRIC CANADA LTD: Toronto

OPERATIONAL TESTING - Continued 3 cycle, will automatically reset the lockout circuit, extinguishing the overcurrent-lockout indicating lamp.

To simulate lockout, momentarily press, then release the simulate-overcurrent pushbutton for the source serving the load and, at the same time, press and hold the associated simulate-loss-of-source pushbutton. (This will simulate a fault that is cleared by the source- side protective device.) If the simulate-loss-of-source pushbutton is pressed long enough for the associated loss-of-source timer to complete its cycle, the inter- rupter switch*serving the load will open-and the other interrupter switch will remain open and locked out.

and closing operations, actually, if the switch operators are in the @ Although the term “interrupter switch” is used in referring to opening

decoupled condition, only the operators will move to their switch-open and switch-closed positions.

To cancel the lockout condition, place the man- uaVautomatic operation selector switch in the manual position and press the overcurrent-lockout reset pushbutton on the Type AT-2 control. The overcur- rent-lockout indicating lamp will extinguish. To restore service, press the “Close” pushbutton on the preferred- source switch operator (or the alternate-source switch operator if preferred-source voltage is not available). Alternately, following cancellation of the lockout condition, service can be restored by placing the manual/automatic operation selector switch in the automatic position. Immediately, the preferred-source interrupter switch will close (or the alternate-source interrupter switch will close if the preferred-source voltage is not available).

Before Walking Away. . . So that the AT-2 control is ready for automatic operation, make sure that the selector switches on the device are correctly positioned. Also make sure that the “ready” lamp is lighted. See “Conditions required to light ‘ready’ indicator lamp,” as listed on the front panel of the control and at the right.

Note: A lighted “ready” lamp indicates that the status of associated components is normal, but an absence of illumination does not necessarily mean that the control is inoperative. For example, when transfer to the alternate source occurs, the lamp extinguishes, but the control is ready for any subsequent programmed automatic operation required by a change in source conditions. Likewise, if the switch operators are decoupled, the “ready” lamp is extinguished but the control is fully oper- ative. Of course, the control will not operate if, for

example, the manual/automatic operation selector switch is in the manual position or an overcurrent- lockout condition exists-as indicated by illumina- tion of the overcurrent-lockout indicating lamp.

Conditions required to light “ready” indicator lamp: 1. Manual/automatic operation selector switch in

2. Preferred switch operator closed. 3. Alternate switch operator open. 4. Lamp operable (push to test). 5. Operators coupled to switches. 6.Open-phase detection selector switch (if fur-

7.Overcurrent-lockout indicator reset (if

automatic position.

nished) in on position.

furnished).

INSTRUCTION SHEET 5 1 4.5 1 0 S&C ELECTRIC COMPANY Chicago Page 9 of 15 S&C ELECTRIC CANADA LTD.0 Toronto November 7,1988

s&C Source-Transfer Controls In Weatherproof Enclosures Type AT-2 I I OPERATION I Normal Conditions Under normal conditions, with adequate voltage available from both utility sources, the preferred-source interrupter switch is closed and the alternate-source interrupter switch is open with its associated circuit available as a standby. The operation selector switch on the Type AT-2 control is set in the automatic position and both source-voltage indicating lamps, as well as the automatic-transfer “ready” indicating lamp, are lighted. See “Conditions required to light ‘ready’ indicator lamp” listed on the Type AT-2 control and on page 9.

Transfer Induced by Loss of Source Voltage At installations using a single line-to-line or line-to- ground connected voltage transformer per source for voltage sensing, the Type AT-2 control continuously monitors the signal-input voltage level on each of the two sources and compares these inputs to a reference level to determine the status of each source. The control will initiate a loss-of-source transfer when both of the following conditions exist: (a) The signal-input voltage from the sensed phase of

the source serving the load is reduced below a preset level (normally factory-set at 1.77 volts),? for a period of time sufficient to confirm that the condition is not transient (normally factory-set at 5 seconds), and

(b) The signal-input voltage from the sensed phase of the standby source exceeds a preset level (normally factory-set at 2.19 volts).f

At installations using two line-to-line connected voltage transformers (and one auxiliary transformer) per source for voltage sensing or three line-to-ground

connected voltage transformers per source for voltage sensing, the Type AT-2 control continuously monitors the signal-input voltage level on each phase of the two sources and compares these inputs to a reference level to determine the status of each source. The control will initiate a loss-of-source transfer when both of the following conditions exist: (a) The signal-input voltage from one or more phases

of the source serving the load is reduced below a preset level (normally factory-set at 1.77 volts),? for a period of time sufficient to confirm that the condition is not transient (normally factory-set at 5 seconds), and

(b) The signal-input voltages from all phases of the standby source exceed a preset level (normally factory-set at 2.19 volts).?

Thus, the control will not allow a transfer to an inadequate source. Also, repeated transfers are pre- cluded in the event that both sources are below the acceptable level. (As a matter of information, the source- voltage indicating lamps maintain full brilliance until a source signal-input voltage is reduced to the preset level--1.77 volts or 2.19 volts-at which point the applicable lamp will completely extinguish.)

If transfer to the alternate source occurs, the “ready” indicating lamp will extinguish-signaling that normal conditions no longer exist.

t As a point of information, 1.77 volts is equivalent to 85 volts on a 120-volt basis (corresponding to approximately 71% of system line-to- ground voltage) and 2.19 volts is equivalent to 105 volts on a 120-volt basis (corresponding to approximately 87% of system line-to-ground voltage).

5 1 4m5 1 0 INSTRUCTION SHEET Page 10 of 15 S&C ELECTRIC COMPANY. Chicago November 7,1988 S&C ELECTRIC CANAOA LTO: Toronto

I OPERATION - Continued I Return Transfer Upon return of the preferred-source voltage for a period of time sufficient to establish that the return is not temporary, automatic retransfer to that source will occur if the operating-mode selector switch on the Type AT-2 control is positioned for automatic return. The retransfer may be either closed transition or open transition, as pre-established by the positioning of the open-transition-return/closed-transition-return oper- ating-mode selector switch.

With closed transition return, the alternate-source interrupter switch will open after the preferred-source interrupter switch has closed, so there is no interruption of service to the load. On the other hand, with open transition return-which prevents an automatic opera- tion that would parallel the power sources-the alter- nate-source interrupter switch will open prior to closing of the preferred-source interrupter switch.

If the operating-mode selector switch is positioned for hold return, retransfer to the preferred source must be accomplished manually-unless the alternate-source voltage becomes inadequate (and preferred-source voltage is adequate), in which case an automatic open- transition retransfer to the preferred source will take place.

When the load is again served from the preferred source, the “ready” indicating lamp will light.

Transfer Induced by Open-Phase Condition At installations using three line-to-ground connected voltage transformers per source for voltage sensing, the Type AT-2 control may be furnished with optional open-phase detection feature (catalog number suffix “-Ll”). This feature protects the load from any source- side open-phase condition whether caused by utility-

line burndown, broken conductors, single-phase switch- ing, equipment malfunctions, or single-phasing result- ing from blown source-side fuses.

When equipped with the open-phase detection feature, the control will initiate an automatic source transfer-in the manner previously described on ‘page 10 under the heading “Transfer Induced by Loss of Source Vo1tage”“as a result of either loss of source or source-side open-phasing when both of the following conditions exist: (a) The signal-input voltage from one or more phases

of the source serving the load is reduced below a preset level (normally factory-set at 1.77 volts)$ or the signal-input phase-voltage unbalance exceeds 15%A for a period of time sufficient to confirm that the condition is not transient (normally factory-set for 5 seconds); and

(b) The signal-input voltages from all phases of the standby source exceed a preset level (normally factory-set at 2.19 volts); and the signal-input phase- voltage unbalance is less than 1 5 % A

Thus, the control will not allow a transfer to an inadequate source. Also, repeated transfers are pre- cluded in the event that both sources are below the acceptable level. (As a matter of information, the source- voltage indicating lamps maintain full brilliance until a source signal-input voltage is reduced to the preset level--1.77 volts or 2.19 volts-or unti2 the signal-input phase-voltage unbalance exceeds 15%, at which point the applicable lamp will completely extinguish.)

A As a point of information, 1.77 volts is equivalent to 85 volts on a 120-volt bass (corresponding to approximately 71% of system line-to- ground voltage) and 2.19 volts is equivalent to 105 volts on a 120-volt basis (corresponding to approximately 87% of system line-to-ground voltage). The 15% phase-voltage unbalance is equ~valent to 18 volts on a 120-volt basis.

INSTRUCTION SHEET 5 1 4 4 1 0 S&C ELECTRIC COMPANY Chicago Page 11 of 15 S&C ELECTRIC CANADA LTD.0 Toronto November 7,1988

SBC Source-Transfer Controls In Weatherproof Enclosures Type AT-2 I I OPERATION - Continued I

Upon return of the preferred-source phase voltages to their normal, balanced state, retransfer to that source can be accomplished as described on page 11 under “Return Transfer.” Overcurrent Lockout When the optional overcurrent-lockout feature (catalog number suffix “-KI” or “-K2”) is included, it prevents an automatic transfer operation that would close a source interrupter switch into a fault, thereby avoiding further utility system disturbance.

If the “-K1” version has been furnished, three Fisher Pierce Series 1301 Powerflex Line Post Current Sensors are used at each source for current sensing. An overcurrent in excess of 200 amperes, 400 amperes, 600 amperes, or 1200 amperes $ detected by one of the current sensors will set up the lockout circuit in the Type AT-2 control to prevent the alternate-source interrupter switch from closing. The overcurrent- lockout indicating lamp will light.

If the “-K2” version has been furnished, three current transformers are used at each source for current sensing. An overcurrent of 5 amperes§ or greater in the secondary circuit of one of the current transformers will set up the lockout circuit in the Type AT-2 control to prevent the alternate-source interrupter switch from

1 Field-selectable.

0 The current transformer ratio should be selected accordingly.

closing. The overcurrent-lockout indicating lamp will light.

If the overcurrent is due to a fault that is cleared by the source-side protective device, the prolonged loss of source voltage will cause the preferred-source interrupter switch to open, and the lockout circuit will prevent the alternate-source interrupter switch from closing into the fault. (Conversely, if the load is being served from the alternate source, the above-described preferredlalternate functioning will be reversed.) After the fault has been located and repaired, the manual/ automatic operation selector switch on the Type AT-2 control must first be placed in the manual position and the overcurrent-lockout reset pushbutton pressed to cancel the lockout condition-and to extinguish the overcurrent-lockout indicating lamp. Then, to restore service to the load, the manual/automatic operation selector switch must be placed in the automatic position. Immediately, the preferred-source interrupter switch will close and the “ready” lamp will light, or, if preferred-source power is not available, the alternate- source interrupter switch will close but the “ready” lamp will not light.*

If the overcurrent is due to a fault that is cleared by feeder fuses, no switching will occur since loss of source voltage is not of sufficient duration to initiate * One of the conditions requlred to hght the “ready” lamp is that the preferred-source interrupter switch be closed and the alternate-source interrupter switch be open.

5 1 4.5 1 0 INSTRUCTION SHEET Page 12 of 15 S&C ELECTRIC COMPANY Chicago November 7,1988 S&C ELECTRIC CANADA LTD:Toronto

OPERATION - Continued 1 opening of the source interrupter switch serving the has been cleared (by the feeder fuse) will actuate the load. In this case, although the fault current initially overcurrent-lockout-reset timer. After the preset period sets up the lockout circuit to prevent automatic closing of time (normally factory-set at 20 seconds) the lockout of the standby-source interrupter switch (and the circuit will automatically reset and the Type AT-2 overcurrent-lockout indicating lamp lights), the subse- control will return to its previous “normal” state (and quent return of normal source voltage after the fault the lockout indicating lamp will extinguish).

No routine maintenance is recommended for the S&C lockout indicating lamp, as well as any other indicating Source-Transfer Control-Type AT-2 other than an lamp not lighted, by pushing on its lens. These lamps occasional exercising, in the manner described on have a life expectancy of two years under continuous pages 8 and 9, about once per year to verify that it and operation. Experience has shown that, if any lamp fails, its associated switch operators are operational. all lamps should be replaced. Occasionally, check functioning of the overcurrent-

INSTRUCTION SHEET 5 1 4 4 1 0 S&C ELECTRIC COMPANY 9 Chicago Page 13 of 15 S&C ELECTRIC CANADA 1TD:Toronto November 7,1988

SSC Source-Transfer Controls In Weatherproof Enclosures Type AT-2 I I SPECIFICATIONS 1 SBC Source-Transfer Control- Type AT92 In Weatherproof Enclosure Control Circuit Voltage, Nominal ........................ .120 v ac Voltage, Operating Range ............ .80 to 140 v ac Current. ........................ . lo0 milliamperes Fuse Rating ........................... KTK-R-10 Operating Temperature Range Ambient Inside Enclosure . . . . . . . .-40°F to +160°F Signal-Input Circuits Voltage Input, Nominal . . . . . . . . . . . . . .2.5 v rms Voltage-Level Detector (loss of source)

Factory Setting . . . . . . . . . . . . . . . .1.77 v rms* Adjustment RangeA . . . . . . . . .1.67 to 2.19 v rms

Factory Setting . . . . . . . . . . . . . . . .2.19 v rmsm Adjustment RangeA . . . . . . . . . .1.87 to 2.5 v rms

(over ambient temperature range) . . . f 3% of setting

Voltage-Level Detector (return of source)

Voltage-Level Accuracy

Current-Level Detector-Using Fisher Pierce Series 1301 Powerflex Line Post Current Sensors (optional)

Adjustment Range.. ............... .200,400,600, ........................... .or 1200 amperes rms

Accuracy . . . . . . . . . . . . . . . ,* 15% of setting79 Current-Level Detector-Using Current Transformers (optional)

Factory Setting0 . . . . . . . . . . . . .5 amperes rms Accuracy . . . . . . . . . . . . . . . . .+ 5% of settingf

Factory Setting (2.5 v ac = 100%). . .15% unbalance@ Frequency Range . . . . . . . . . . . . .60+ 0.3 hertzf

Open-Phase Detector (optional)

Timing Factory Setting

62A and 62P . . . . . . . . . . . . . . . . . . . .5 seconds 2P . . . . . . . . . . . . . . . . . . . . . . . . . . 3 minutes 62LR (optional) . . . . . . . . . . . . . . . . .20 seconds

62A and 62P . . . . . . . . . . . . . . . . 1 to 30 seconds or 10 to 300 seconds.

2P . . . . . . . . . . . . . . . . . . . . . . '/2 to 15 minutes 62LR (optional) . . . . . . . . . . . . . . 1 to 30 seconds

Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . .f 3% Output-Relay Contact Ratings Current Carrying

Adjustment Range

Continuous . . . . . . . . . . . . . . . . . . . 10 amperes 1-Second . . . . . . . . . . . . . . . . . . . . .50 amperes

Interrupting . . . . . . . 10 amperes, 120 v ac, 80% P.F. Indicating Lamps Chicago Miniature Lamp Works

Sylvania or General Electric Catalog Number . . . . . . . . . . . . . . . . . . CM-382

Catalog Number . . . . . . . . . . . . . . . . . . . . .382

* Equivalent to 85 volts on a 120-volt basis. A Not field-adjustable. . Equivalent to 105 volts on a 120-volt basis.

Sensed at the primary of the current sensors. 7 Allowing for variances In conductor size, conductor spacing, manufacturing tolerances, and operating temperature. 5 Correction factor for Fisher Pierce Series 1301 Powerflex Line Post Current Sensors = 4.45/(3.92+D), where D equals the outs~de diameter of the conductor. 0 Sensed at the secondary of the current transformers. fB Equivalent to 18 volts on a 120-volt basis. 1 For 50-hertz applications, refer to the nearest S&C Sales Office.

Selected by means of a 10-times selector switch.

5 1 4.5 1 0 INSTRUCTION SHEET Page 14 of 15 S&C ELECTRIC COMPANY Chicago November 7,1988 S&C ELECTRIC CANADA LTD: Toronto

I SPECIFICATIONS - Continued 1 TYPE AT-2 SOURCE-TRANSFER CONTROLS IN WEATHERPROOF ENCLOSURES@@

Voltage-Sensing MethodB Catalog Number@

Single-phase, One Voltage Transformer (connected line-to-line or line-to-ground) Per Source 38950

I Three-phase, Two Voltage Transformers (connected line-to-line) Plus One Auxiliary Transforme6 Per Source I 38951 I Three-phase, Three Voltage Transformers (connected line-to-ground) Per’ Source@

~~ ~ ~ ~~

38952

@ For use only wtth S&C Switch Operators-Type AS-1A and (9 For steel structure mounting. For pole mounting, optional pole Type AS-IO utilizing 115-volt 60-hertz or 230-volt 60-hertz motor and mounting bracket is required. See “OPTIONS FOR TYPE AT-2 control voltage, and furnlshed with optional Source-Transfer Control SOURCE-TRANSFER CONTROLS I N WEATHERPROOF ENCLO- Compatibility. SURES” table below. @ The S&C Test Accessory available for Type AT Source-Transfer (3 Furnished by S&C. Controls in S&C Metal-Enclosed Gear cannot be used. (9 This voltage-sensing method is required if open-phase detection @ Using customer-furnished voltage transformers. feature (catalog number suffix “-Ll”) is specified. See “OPTIONS FOR

TYPE AT-2 SOURCE-TRANSFER CONTROLS IN WEATHER- PROOF ENCLOSURES” table below.

Optional features which have been included in the S&C Source-Transfer Control-Type AT-2 are signified by the addition of one or more suffixes to the catalog

number of the control, as indicated in the following table:

OPTIONS FOR TYPE AT-2 SOURCE-TRANSFER CONTROLS IN WEATHERPROOF ENCLOSURES Suffix

For Source-

Control Catalog Number

A d W to Item

Catalog Number

Source-Transfer Tranrfer Control

Overcurrent-Lockout Feature-Using Fisher Pierce Series 1301 Powerflex Line Post Current Sensors. Includes field-adjustable 200-A-400-A-600-A-1200-A level-detector switch, field-ad’ustable 1-30 second reset timer dial,$ lockout-Indicating lamp, and manual-reset pushbuttond

-K1 All

Overcurrent-Lockout Feature-Using Current Transformers. Includes overcurrent relay, fleld-adjustable 1-30 second reset timer dial,$ lockout-indicating lamp, and manual-reset pushbutton@

All -K2

Open-Phase Detection Feature. Develops and monitors the phasor sum of the line-to-ground voltages to initiate source transfer when source-side open-phase condition occurs-even if the open phase is 38952. -L1 backfed by connected loads such as motors, etc.

Remote-Indication Feature. Includes provisions to permit remote monitoring of the presence or absence of both source voltages, the operating mode for the source-transfer control (i.e., automatic or manual), and the status of the “ready” indicator. Also includes provisions to permit remote indication of overcur-

All -A1

rent lockout (where applicable)

Pole Mounting Bracket with Hardware All -P1

0 Three customer-furnished Fisher Pierce Powerflex Line Post Current !should be selected accordingly-and should take into account the Sensors are required for each source. The level-detector switch setting ;anticipated emergency peak-load current of the system, so as to preclude should take into account the emergency peak-load current of the system, nuisance lockouts. so as to preclude nulsance lockouts. 1: Factory-adjusted for 5 seconds. @ Three customer-furnished current transformers are required for each . Using-three-phase voltage sensing by of three customer- source. In that the overcurrent relay is factory-set to respond to a secondary current of 5 amperes or greater, the current-transfomer ratio furnished per source, connected line-to-ground.

INSTRUCTION SHEET 5 1 4-5 1 0 S&C ELECTRIC COMPANY* Chicago Page 15 of 15 S&C ELECTRIC CANADA LTD.0 Toronto November 7,1988