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Type D Knife Switches by Filnor, Inc |
| All current carrying parts of Type D knife switches are milled and provided with a corrosion resistant finish. Designed for back-connection, these switches are furnished without bases for mounting on insulating panels for customers' switchboards. |
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KNIFE SWITCHES |
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 Filnor has over 700 standard Knife Switces listed. The electrical rating of the switches range from 30 Amperes at 250 Volts AC/DC to 6000 Amperes at 600 Volts AC/DC. All of these standard switches carry the Underwriters Laboratories listing.
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< FRONT CONNECTED TYPE A BACK CONNECTED TYPE L >
 Section B - Type D Back Connected Knife Switches 3.5 MBHEAVY-DUTY KNIFE SWITCHES SECTION B Class 9851 Back Connected Knife Switches with Stud and Nut Terminations Construction: All current carrying parts of Type D knife switches are milled and provided with a corrosion resistant finish. Designed for back-connection, these switches are furnished without bases for mounting on insulating panels for customers' switchboards. Switches rated 1200 amperes and larger are shipped on throw-away bases as standard. Prices will be quoted upon request for switches, rated 800 amperes and smaller, mounted on throw-away bases. Connection are made to Type D switches by means of round studs of hard-drawn copper. Switches rated 600 amperes and smaller are furnished with studs to fit boards from 1/2" to 2" thick. Fusible hinge switches have steel studs and nuts that fit any board 1/2" to 2" thick. The steel studs and screws are only for mounting purposes. No electrical connections are made to fusible hinges.  Field Discharge Switches are used to overcome the high inductive current caused by suddenly opening a generator field. When opening the generator circuit, the field discharge switch closes the field across a resistor allowing the inductive discharge to die out gradually, which might otherwise result in a rupture of field insulation.Upon opening these two-pole switches the discharge blade, which is an offset extension of one of the main blades, makes contact with a high clip. The high clip, which is connected to the resistor, is located between the hinges of the two blades. Another feature of the switch is each pole is equipped with quick-break blades. The discharge blades and the quick-break blades combine to provide a make-before-break operation. Upon opening the switch, the resistance circuit is made before the line-to-field circuit is broken, limiting the field discharge voltage. When closing the switch the discharge blade breaks the resistance circuit before the main blades make contact. Available 60 Amp thru 200 Amp. Larger sizes available upon special order. Ratings: Ampere ratings of Type D, not fusible knife switches are based on a temperature rise of not more than 30 degree C. above an ambient temperature of not more than 40 degrees C. when mounted in open air. Enclosed ratings are based on the switches being mounted in enclosures with adequate ventilation and with bus or cable of appropriate size. Fusible switches are not to be loaded continuously at more than 80 percent of the fuse rating. TYPE D BACK CONNECTED KNIFE SWITCHES Single-throw, Not fusible Open knife switches are used as disconnect switches mounted on switchboards, distribution and control panelboards. Extensive use of knife switches in the heavy industries and laboratories, for control and test panels, where visible disconnects are required. Type D, single-throw, not fusible knife switches have a corrosion resistant finish and low hinges and clips. Designed for back-connection, these switches are furnished without bases for mounting on insulating panels of customers' switchboards. Type D switches can also be furnished mounted on insulating panels. Prices are quoted upon receipt of compete information including panel size. TYPE D BACK CONNECTED KNIFE SWITCHES Double-throw, Non fusible Type D, double-throw, non fusible knife switches are similar in construction to the single-throw version. For applications where it is necessary to manually transfer between two power supplies or two loads, the double-throw switches are particularly well suited. TYPE D BACK CONNECTED KNIFE SWITCHES Single-throw, fusible Fusible Type D knife switches are arranged with fuse holders which will accept standard National Electrical Code fuses. When mounted on a panel the single-throw switch is fusible at the bottom. TYPE D BACK CONNECTED KNIFE SWITCHES Double-throw, fusible Fusible, double throw, Type D knife switches are fusible in both throws. In order to provide clearance between the handle and the fuses, these switches are constructed with low hinges and high clips. TYPE D BACK CONNECTED KNIFE SWITCHES Single or Double-throw, non fusible Field Discharge Switches are used to overcome the high inductive current caused by suddenly opening a generator field. When opening the generator circuit, the field discharge switch closes the field across a resistor allowing the inductive discharge to die out gradually, which might otherwise result in a rupture of field insulation. Upon opening these two-pole switches the discharge blade, which is an offset extension of one of the main blades, makes contact with a high clip. The high clip, which is connected to the resistor, is located between the hinges of the two blades. Another feature of the switch is each pole is equipped with quick-break blades. The discharge blades and the quick-break blades combine to provide a make-before-break operation. Upon opening the switch, the resistance circuit is made before the line-to-field circuit is broken, limiting the field discharge voltage. When closing the switch the discharge blade breaks the resistance circuit before the main blades make contact. Polarity Reversing Switches: Another version of the Type D knife switch is the Polarity Reversing Switch. This switch is two-pole, double-throw and is equipped with standard blades. The cross-connection, used to give the reversing action, is made of copper bus straps mounted between the poles of the front of the switch. Connections to the hinges are made on the front with connections to the clips on the back of the switch. 
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Knife Switch Catalog
