Type SM, SML, and SME j Indoor Distribution INSTRUCTIONS For Installation GENERAL Ç CAUTION The equipment covered by this publication must be selected for a specific application and it must be installed, operated, and maintained by qualified persons who are thoroughly trained and who understand any hazards that may be involved. This publication is written only for such qualified persons and is not intended to be a substitute for adequate training and experience in safety procedures for this type of equipment. The following instructions are for installation of SM-4 and SM-5 Refill Units in S&C Power Fuses Types SM-4Z, SML-4Z, SME-4Z, SM-5S, and SM-5SS, Indoor Distribution and S&C Power Fuses Types SM-4 and SM-5, Outdoor Distribution, as well as preceding models of these fuses. WARRANTY QUALIFICATIONS: For the standard warranty contained in seller s standard conditions of sale (as set forth in Price Sheet 150) does not apply to S&C SM or SML Mountings when installed in conjunction with fuses of other than S&C manufacture, nor does it apply to S&C SM Refill Units and Holders installed in mountings of other than S&C manufacture. Ç IMPORTANT Refill units should be stored in a dry place and kept in the carton until used. Storage indoors, in a clean, dry place, is required for indoor style holders and recommended for outdoor style holders. If an unloaded outdoor holder is stored outdoors, it must not be left in such a position that the glass-epoxy tube inside the porcelain housing can get wet. Store the holder in an upright position and keep the lower ferrule opening closed by the cork inserted at the factory. The gravity-operated rain shield on the lower ferrule of outdoor disconnect 180º opening vertical style holders helps to prevent water and direct from entering the holder when it is left hanging open for short periods of time. However, since the rain shield is not a positive sealing device, the holder should be removed from the mounting when it is not in service. Handle holders especially holders especially holders with refill unit installed with care. Do not drop or throw them. NOTICE S&C Power Fuse Refill Units have silver or nickelchrome fusible elements that are nondamageable; consequently, there is no need to replace unblown companion fuses (on three-phase systems serving three-phase loads) on suspicion of damage following a fuse operation. j Type SME Power Fuses are available in S&C Pad-Mounted Gear, PME Models, only. Supersedes Instruction Sheet dated 9-27-82 1983 Page of 8
Type SM, SML, and SME Indoor Distribution FUSING (Holders equipped with Silencer, Snuffler, Super Snuffler, Muffler, or Sneezer Exhaust-Control Device) S&C Type SM Power Fuse Holders have been furnished with a number of different exhaust-control devices over the years. As the procedure for fusing these holders varies somewhat according to the particular exhaust-control device furnished, it is important that the exhaust-control device be properly identified. Refer to the photos below and determine which device was furnished. SM-4B Muffler SM-4D Sneezer SM-4S Snuffler SM-4Z, SML-4Z, and SME-4Z Silencer SM-5B, SM-5C Muffler SM-5D Sneezer SM-5S Snuffler SM-5SS Super Snuffler Page of 8
FUSING (Holders equipped with Silencer, Snuffler, Super Snuffler, Muffler, or Sneezer Exhaust-Control Device) Note: Steps 1, 2, 9, and 10 (below) apply only to the following Type SM Power Fuse Holders in the disconnect style: SM-4B, SM-5B, and SM-5C Holders furnished with Muffler; SM-4D and SM-5D Holders furnished with Sneezer; and SM-4S Holders furnished with Snuffler. Steps 1, 2, 9, and 10 (below) do not apply to any non-disconnect style holders (including SM-5SS Holders furnished with Super Snuffler), nor to the following holders in the disconnnect style; SM-4Z, SML-4Z, and SME-4Z Holders furnished with Silencer, or SM-5S Holders furnished with Snuffler. Step 4. Unscrew and withdraw the holder cap to which is attached the spring-and-cable assembly. Step 1. Loosen the two screws which secure the lower end fitting to the lower ferrule of the holder. Step 2. Loosen the clamp bolt and pry the clamp apart slightly. Step 5. Screw a refill unit of correct ampere and voltage rating tightly onto the lower end of the spring-and-cable assembly, using the knurled terminal on the spring-andcable assembly to impart a final, hard twist. Do not use a wrench. Before proceeding to Step 6, check to see that the knurled collar at the other end of the refill unit is tight against the shoulder of the refill-unit ferrule. Step 3. Unscrew and remove the exhaust-control device (Silencer, Snuffler, Super Snuffler, Mufler, or Sneezer). A bar or wrench handle can be used to loosen it. Step 6. Insert the combination of spring-and-cable assembly and refill unit into the holder and screw the cap down tight. The final fractional turn should be made with a wrench. Page 3 of 8
Type SM, SML, and SME Indoor Distribution FUSING (Holders equipped with Silencer, Snuffler, Super Snuffler, Muffler, or Sneezer Exhaust-Control Device) Z\, Approx. Exhaust ferrule Step 8. Replace the exhaust-control device, screwing on firmly. To ensure adequate electrical contact with the contact fingers which is essential to the proper performance of the fuse the final, fractional turn of the exhaust-control device must be made with a bar or wrench handle. Step 9. Tighten the two screws which secure the lower end fitting to the lower ferrule of the holder. Step 10. Tighten the clamp bolt. Knurled collar Contact fingers MAXIMUM PULL-THROUGH POSITION DROP-BACK POSITION Step 7. Carefully draw the refill pull-cord out through the holder, against spring tension, until the contact fingers of the holder latch behind the knurled collar of the refill unit. Avoid jerking and excessive overtravel, which may damage low-ampere refill units. Release the refill pull-cord slowly, permitting the colar to rest on the contact fingers. Remove and discard the cord. Do not bend or otherwise alter the shape of the contact fingers. Page 4 of 8
FUSING (Holders not equipped with Silencer, Snuffler, Super Snuffler, Muffler, or Sneezer Exhaust-Control Device) Step 1. If the holder is equipped with a clamp-on type rain shield, loosen the clamp and remove it. (Gravityoperated rain shields, as furnished on outdoor disconnect 180º opening vertical style holders and shown above need not be removed.) Remove the hexagonal clamping nut from the end of the holder. Step 3. Screw a refill unit of correct ampere and voltage rating tightly onto the lower end of the spring-and-cable assembly, using the knurled terminal on the spring-andcable assembly to impart a final, hard twist. Do not use a wrench. Before proceeding a Step 4, check to see that the knurled collar at the other end of the refill unit is tight against the shoulder of the refill-unit ferrule. Step 2. Unscrew and withdraw the holder cap to which is attached the spring-and-cable assembly. Step 4. Insert thecombination of spring-and-cable assembly and refill unit into the holder and screw the cap down tight. The final fractional turn should be made with a wrench. Page 5 of 8
Type SM, SML, and SME Indoor Distribution INSTALLATION AND ADJUSTMENT Z\, Approx. Knurled collar Exhaust ferrule Contact fingers Step 6. Replace the hexagonal clamping nut, screwing down firmly to lock the refill unit in place. To ensure adequate electrical contact with the contact fingers which is essential to the proper performance of the fuse the final fractional turn of the hexagonal clamping nut must be made with a wrench. If the holder is equipped with a clamp-on-type rain shield, replace the rain shield and tighten the clamp. MAXIMUM PULL-THROUGH POSITION DROP-BACK POSITION Step 5. Carefully draw the refill pull-cord out through the holder, against spring tension, until the contact fingers of the holder latch behind the knurled collar of the refill unit. Avoid jerking and excessive overtravel, which may damage low-ampere refill units. Release the refill pull-cord slowly, permitting the colar to rest on the contact fingers. Remove and discard the cord. Do not bend or otherwise alter the shape of the contact fingers. Page 6 of 8
RE-FUSING BLOWN FUSES Step 1. Remove the exhaust-control device or the hexagonal clamp nut, as described under Fusing. Step 2. Grasp the knurled collar of the blown refill unit and withdraw the refill unit from the holder. Discard the blown refill unit. Step 3. Unscrew the holder cap and withdraw the springand-cable assembly. Step 4. Unscrew and discard the arcing terminal of the blown refill unit. Wipe clean all contact surfaces but do not clean with an abrasive as the silver plating may thus be damaged. If the spring is damaged, install a new springand-cable assembly. Step 5. After a high-magnitude fault, wipe clean the interior of the fuse holder to remove any dust and metallic particles that may be present. Step 6. After a high-magnitude fault, carefully inspect the inside of the exhaust-control device. If the copper mesh shows significant erosion, as a result of an extremely high fault, replacement of the exhaust-control device is recommended. Step 7. Using a new refill unit of correct ampere and voltage rating, fuse and reassemble as described under Fusing. Page 7 of 8
Type SM, SML, and SME Indoor Distribution RE-FUSING UNBLOWN FUSES S&C Power Fuse Refill Units have silver or nickel-chrome fusible elements that are nondamageable; consequently, there is no need to replace unblown companion fuses (on three-phase systems serving three-phase loads) on suspicion of damage following a fuse operation. If an unblown refill unit is to be replaced, for example, to change ampere rating, follow the procedure listed below. Step 1. Remove the exhaust-control device or the hexagonal clamp nut, as described under Fusing. Step 3. Unscrew and remove the knurled collar from the refill unit and allow the refill unit to slide slowly back into the holder. Step 4. Unscrew the holder cap and withdraw the springand-cable assembly and refill unit. Unscrew the refill unit from the spring-and-cable assembly, replace it with a refill unit of the desired ampere rating, and reassemble as described under Fusing. Step 5. Replace the knurled collar that was removed in Step 3, above. to simplify reapplication of the replaced refill unit, insert a strong cord 280 in length through the hole referred to in Step 2, above. Ç IMPORTANT If the replaced refill unit is not to be used immediately, place it in a polyethylene bag and then in a refill-unit carton. Make the carton with the correct ampere rating and store it in a dry place. Step 2. Insert a cord or wire through the small hole in the projecting threaded portion of the ferrule of the refill unit. Pull the refill unit outward about Z\, inch. Printed in U.S.A. Page 8 of 8