Cutler-Hammer. Instructions for Potential Transformer and Auxiliary Control Power Disconnecting Means for Use in Ampgard Lineups, 7.2 kv I.B.

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1 Cutler-Hammer Instructions for Potential Transformer and Auxiliary Control Power Disconnecting Means for Use in Ampgard Lineups, 7.2 kv DANGER HAZARDOUS VOLTAGE. READ AND UNDERSTAND THIS BOOKLET IN ITS ENTIRETY BEFORE INSTALLING OR OPERATING CONTROLLER. INSTALLATION, ADJUSTMENT, REPAIR AND MAINTENANCE OF THESE CONTROLLERS MUST BE PERFORMED BY QUALIFIED PERSONNEL. A QUALIFIED PERSON IS ONE WHO IS FAMILIAR WITH THE CONSTRUCTION AND OPERATION OF THIS EQUIPMENT AND THE HAZARDS INVOLVED. THE EQUIPMENT Potential Transformer (PT) and Auxiliary Control Power (ACP) disconnect switch assemblies are enclosed in individual cells 15" (38 cm) high and the full width of the Ampgard enclosure in which they are mounted. The potential transformer versions are used wherever PT s with a separate disconnecting means are required for either protection or metering circuits. The potential transformers they disconnect are usually connected to the bus bar system of an Ampgard lineup rather than to an individual branch circuit. The PT disconnect allow deenergizing and access to the PT's without disrupting the main power source. Fig. 1 PT Disconnect Installed 4 6 Auxiliary Control Power (ACP) versions are used wherever more than 5 kva of control power are required for any single Ampgard motor controller or it is necessary to source control power from remote equipment. ACP disconnects feeding transformers larger than 2kVA incorporate a key-operated mechanical interlock paired with a similar device interlocking the low-voltage circuit breaker which disconnects the load fed from the secondary of the transformer supplying control power. The keyoperated mechanical interlocks are selected such that the single key may be withdrawn only when the ACP disconnect is ON and the low-voltage circuit breaker is OFF. The ACP is available as a fused switch with the fuses for the transformer primary located within the switch (5 Amp, 5 kv maximum) or as an unfused switch, in which case the primary fuses must be mounted externally. Fig. 2 View Showing Transformer Primary Grounded When Operating Handle is in OFF Position 7 Both PT and ACP assemblies ground the transformer primary when in the OFF position. See Figure 2.

2 Page 2 GENERAL DESCRIPTION A view of the right hand, or mechanism, end of the PT disconnect cell is shown in Figure 3. PT s rated above 5 kv must be mounted externally to the PT Disconnect, in which case an ACP configuration (without a key interlock on the secondary) is provided. PT disconnect configuration with internally-mounted PT s is described. The ACP configurations use a similar mechanism, with insulated mounting provisions for the line fingers and fuses. The PT s (1) are mounted on a cradle, or tray (2), which can be rotated 90 about a fixed pivot (3). The PT s have primary fuses (4) and fuse clips terminating in a flexible line finger (5) mounted on their top surface. The fuse clips at the opposite or lower end of the fuses, terminate in a shorter, flexible grounding finger (6) (see Figure 2), which, when the PT s have been rotated to the OFF position, contact a grounding bar (7), to short the PT primary windings to ground. Note that the top, or line end finger of the fuse, is mounted to the transformer by a bracket that provides mechanical support only. It has no electrical connection to the transformer winding. Conversely, a similar supporting bracket at the bottom, or grounding finger end of the fuse, also provides the electrical connection to the transformer primary terminal. Rotation of the PT tray is controlled by the operating handle (8) which drives the system of levers that operates the PT tray and insulating shutter. The main drive lever (9) rotates about a second fixed privot (10) and has a cam surface between ON and OFF detents. A springloaded cam follower (11) engages these detents to give the handle (8) a positive feel for the ON and OFF positions. OPERATION a) Closing Stroke As the operating handle (8) is moved from the OFF to the ON position, the PT s and the tray (2) rotate, and an insulating shutter mounted on the rear barrier (12) (See Figure 6) slides open. After the shutter opens, the flexible line fingers (5) mounted on the PT s pass through the openings (13) in the barrier, and make contact with the line terminals (14). The wiping action of the fingers on the line terminals insures good electrical contact. Immediately after the line fingers make contact, the interlock lever (15) (See Figure 3) operates the auxiliary contacts (16), and the transformer secondary circuits are closed. b) Opening Stroke As the handle (8) is moved from the ON to the OFF position, auxiliary contacts (16) open, and unload the transformer secondary circuits before the primary line contacts separate. This action limits the arcing current at the line contacts to the transformer shutter closes to isolate the line terminals from the PT compartment. When the PT s reach the OFF position, grounding fingers (6) (Figure 2) connect the line fingers to the ground bar (7). DOOR INTERLOCKS Two mechanical interlocks are incorporated into the mechanism. The user should be familiar with the functions of these interlocks before putting the unit into service. The first interlock prevents the disconnect door from being opened when the operating handle is in the ON position. This is achieved with a latch (17) (Figure 3) attached to the handle mechanism which engages a catch (18) (Figure 7) mounted on the door. If it is necessary, this interlock can be deliberately defeated by turning the defeater screw (20) (Fig. 3) counterclockwise. (See WARNING note below.) This screw is located on the operating mechanism faceplate and incorporates a coinproof slot, thereby requiring a tool to operate. The second interlock prevents moving the operating handle from the OFF to the ON position while the door is open. This is achieved with a latch (21) (Fig. 3) that engages the handle mechanism output bar (22). The latch (21) has a finger spring (23) that rotates the latch (21) to release the interlock when the door is closed and fastened. This interlock can be deliberately defeated by pushing in the finger spring (23). (See WARNING note below.) WARNING DEFEATING EITHER INTERLOCK PERMITS THE USER TO OBSERVE THE OPERATION OF THE ASSEMBLY DURING INSTALLATION OR MAINTENENACE. HOWEVER, DEFEATING INTERLOCKS IS A VERY HAZARDOUS PROCEDURE AT ANY TIME. THE USER MUST BE FULLY AWARE OF THE DANGERS, BE FAMILIAR WITH THE ASSEMBLY AND INTERLOCK OPERATION, AND TAKE ALL APPROPRIATE SAFETY PRECAUTIONS BEFORE DEFEATING ANY INTERLOCK.

3 Page 3 ADJUSTMENTS Tray With the tray (2) (Figure 3) in the OFF position, the grounding fingers (6) (Figure 2) should be touching the ground bar (7). If they are not touching, or if the fingers are deflected by more than 0.063" (1.6 mm) then adjust the location of the OFF detent slightly as follows: a) Loosen the two 0.25"-20 bolts (located on the underside of the bottom pan) holding the pivot bracket (25) (Figure 3) in position. These bolts engage a threaded nut plate located inside the pivot bracket so that the nut plate cannot turn. WARNING BE SURE THAT ALL POWER TO THE SWITCH HAS BEEN PROPERLY DE-ENERGIZED, AND ALL NECESSARY SAFETY PRECAUTIONS HAVE BEEN TAKEN PRIOR TO BEGINNING ANY ADJUSTMENTS Fig. 3 Close-Up View of PT, Fuses, Auxiliary Contacts, and Operating Mechanism

4 Page 4 ADJUSTMENTS (Continued) b) Move the pivot bracket (25) either forward, or back slightly, until the tray is positioned properly, as explained above. c) Tighten the two 0.25"-20 bolts and recheck the adjustment. Auxiliary Contacts One or more Type L64 auxiliary contact units, sometimes used as electrical interlocks, are held in place by two bolts (26) (Figure 3). If adjustment is required: a) Place the tray in the ON position. b) Loosen the two bolts (26). c) Move the contact units up or down to establish 0.063" (1.6 mm) of contact overtravel. d) Secure the bolts (26). e) Recheck the adjustment. f) Check to make sure that the operating lever (15) strikes both contact unit plungers at the same time. Bend the lever slightly, if necessary. Door Interlocks When the door interlock is properly adjusted, a slight downward pressure on the operating handle (8) when it is in the OFF position, should release the catch (18) (Figure 7) mounted on the door, and the door should be free to open. Similarly, on closing the door, the bottom edge of bracket (19) should clear the top edge of the bottom pan by not more than 0.125" (3 mm). If adjustment is required: a) Place the tray in the OFF position and open the door. b) Loosen the two bolts (27). c) Move latch (18) and bracket (19) either up or down to meet the conditions described above. d) Retighten the bolts (27) and check the adjustment and operation of the interlock Fig. 4 Two PTs in Open Delta for Typical Metering Circuit Fig. 5 Three PT s in Wye-Delta Connection for Typical Ground Detection Circuit

5 Page 5 COMMON POTENTIAL TRANSFORMER CIRCUITS The most commonly used potential transformer secondary connection diagrams are shown in Figures 4 and 5. START-UP PRECAUTIONS Before attempting to energize a newly installed disconnect assembly, study the wiring diagram and available instruction literature. Learn the hazards involved. DANGER HAZARDOUS VOLTAGE. READ AND UNDERSTAND THIS BOOKLET IN ITS ENTIRETY BEFORE INSTALLING OR OPERATING THE DISCONNECTING MEANS. INSTALLATION, ADJUSTMENT, REPAIR AND MAINTENANCE OF THIS EQUIPMENT MUST BE PERFORMED BY QUALIFIED PERSONNEL. A QUALIFIED PERSON IS ONE WHO IS FAMILIAR WITH THE CONSTRUCTION AND OPERATION OF THIS EQUIPMENT AND THE HAZARDS INVOLVED. Fig. 6 Rear View of a Three PT Disconnect Assembly 27 In general, be sure that: 1) The power supply to the equipment is OFF, and all safety precaustions have been taken to ensure that an examination and any adjustments can be made safely. 2) The intended power supply voltage agrees with the PT nameplate data. 3) The primary (4) and secondary (24) fuses have been properly installed as shown in Figure 3. 4) The mechanism works smoothly, the shutter slides easily, and the line fingers enter the aperatures in the rear barrier and make contact with at least 0.25" (6mm) of wipe on the line terminals. 5) The auxiliary contacts (16) (Figure 3) open before the line contacts separate. (See ADJUSTMENTS below, if adjustments are required). 6) The line terminals are properly grounded in the OFF position. (See Figure 2.) See ADJUSTMENTS above, if adjustment is required). 7) The door interlocks are properly adjusted and effective. 8) The operating handle is in the OFF position. The door is closed and fastened. The unit is now ready to be energized. Fig. 7 Interlock to Prevent Door Opening While Operating Handle Is in the ON Position

6 Page 6 CONTROL POWER APPLICATIONS The maximum rated exciting currents that Auxiliary Control Power (ACP) disconnect switches can interrupt are shown in Table I, expressed in terms of control power transformer size where the ACP disconnect controls the power to the primary winding of the transformers. The maximum fuse to be used in this primary circuit is rated 10 amperes. To insure that the ACP disconnect is never subjected to more than transformer magnetizing current at the time of opening a system of key-operated mechanical interlocks must be used. See Page 1 for details. A single-phase control power transformer up to 2kVA (5 kv maximum voltage) can be mounted inside the ACP disconnect. Any transformer mounted externally to the ACP disconnect will be key-interlocked with the disconnect to insure that the disconnect is only required to interrupt the transformer s charging current, and not load current. The maximum continuous current rating of the switch is 10 amps and its limited interrupting rating is intended to only interrupt a transformer s charging current and not its load current. SWITCH MAINTENANCE All work on this switch should be done with the main circuit disconnect device open, and using a separate source of control power to test when necessary. Before applying external control circuit power, make certain that the control circuit is electrically isolated, to prevent feedback into a control power transformer that could be hazardous. DANGER WARNING: ALL WORK ON THIS EQUIPMENT SHOULD BE DONE WITH THE MAIN DISCONNECT DEVICE OPEN. AS WITH ANY EQUIPMENT OPERATING AT THIS VOLTAGE, THERE IS DANGER OF ELECTROCUTION AND/OR SEVERE BURNS. MAKE CERTAIN THAT POWER IS OFF. TABLE I. DISCONNECT SWITCH RATINGS Voltage Rating Maximum Single Phase Single Phase Control Power 15 kva 20 kva Transformer Three Phase Three Phase To Be Used 25 kva 35 kva The basic principles to be followed in the maintenance of all electrical equipment are: (1) keep conducting parts as good conductors and (2) keep insulating parts as good insulators, i.e., tighten and clean. A set of three flexible primary fingers, primary fuses, fuse mountings and ground fingers are available as renewal parts. Order Style No. 2147A95G09. See Table II for replacement auxiliary contacts. TABLE II. TYPE L64 AUXILIARY CONTACTS Part Number 843D943G21 843D943G22 843D943G23 Circuit Combination Provided By One Auxiliary Contact Unit Assembly One Normally-Open and One Normally-Closed Two Normally-Open Two Normally-Closed Fig. 8 Typical ACP Connection Diagram

7 Page 7 INDEX PAGE Adjustments... 3 Auxiliary Contact Adjustment... 4 Auxiliary Contact Replacement... 7 Auxiliary Control Power Applications... 1 Auxiliary Control Power Interlocking... 1 Auxiliary Control Power Ratings... 6 Closing Stroke... 2 Component Identification... 3 Control Power Ratings... 6 Disconnect Switch Operation... 2 Door Interlocks... 2 Door Interlock Adjustment... 4 Maintenance... 6 Mechanical Construction... 2 Opening Stroke... 2 Potential Transformer Applications... 4, 5 Primary Circuit Grounding... 1 Ratings, Control Power... 6 Start-Up Precautions... 5 Tray Adjustment... 3 Warnings... 1, 2, 5, 6

8 Page 8 Cutler-Hammer 221 Heywood Road Arden, NC Printed in U.S.A./CCI