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Standard Duty
Mil Duty

 Power Technical Services, Inc.
11336 Pennywood, Baton Rouge, LA 70809
(225) 272-2113 

Fax: (225) 275-2602

Customize Your Own Switch Contact Configuration Using This Form

 

 

Heavy Duty Industrial Switches

Explosion proof, made to stand up to the harsh demands of the steel mills, chemical plants, petroleum refineries and other industrial applications, we make switches with mill-duty durability. These switches, requiring constant and hard usage, are designed for 1/8 to 2-inch thick panel mounting and are available with up to 14 stages (14 control circuits).

If you need them, watertight and dust-tight enclosures can be furnished

Ratings

Mill Duty switches are rated for 10 ampere continuous duty.  Other ratings are identical to the standard 210 switches.

Accessibility

Snap-on covers are quickly removed for easy access. The terminal arrangement at the bottom of the switch permits wiring without removing the covers.  All terminals are clearly marked to identify the connection from the wiring diagram.  You can access the return spring from the rear of the switch, and replace it by removing the rear end plate.

Explosion proof, made to stand up to the harsh demands of the steel mills, chemical plants, petroleum refineries and other industrial applications, we make switches with mill-duty durability. These switches, requiring constant and hard usage, are designed for 1/8 to 2-inch thick panel mounting and are available with up to 14 stages (14 control circuits).

If you need them, watertight and dust-tight enclosures can be furnished

Ratings

Mill Duty switches are rated for 10 ampere continuous duty.  Other ratings are identical to the standard 210 switches.

Accessibility

Snap-on covers are quickly removed for easy access. The terminal arrangement at the bottom of the switch permits wiring without removing the covers.  All terminals are clearly marked to identify the connection from the wiring diagram.  You can access the return spring from the rear of the switch, and replace it by removing the rear end plate.

Flexibility

Each pair of stationary contact fingers is mounted on an individually molded phenolic block.  You can replace or inspect parts right at the installation.

 

Explosion proof, made to stand up to the harsh demands of the steel mills, chemical plants, petroleum refineries and other industrial applications, we make switches with mill-duty durability. These switches, requiring constant and hard usage, are designed for 1/8 to 2-inch thick panel mounting and are available with up to 14 stages (14 control circuits).

If you need them, watertight and dust-tight enclosures can be furnished

Ratings

Mill Duty switches are rated for 10 ampere continuous duty.  Other ratings are identical to the standard 210 switches.

Accessibility

Snap-on covers are quickly removed for easy access. The terminal arrangement at the bottom of the switch permits wiring without removing the covers.  All terminals are clearly marked to identify the connection from the wiring diagram.  You can access the return spring from the rear of the switch, and replace it by removing the rear end plate.

Flexibility

Each pair of stationary contact fingers is mounted on an individually molded phenolic block.  You can replace or inspect parts right at the installation.

Installation and Operation

The installation and dismantling procedures for mill duty switches, as well as operating characteristics, are identical to standard 210 switches.

Construction

All parts subjected to wear have increased strength and are made of high-quality stainless steel or beryllium copper to extend the life of the switch. Generally, construction is similar to the standard 210 switches when 10 or less stages are used. When 11 or more stages are used, phenolic blocks are added to the top and secured with studs and bolts to add strength. Upper studs, lower studs and the shaft fit through the end plates, giving mill duty switches extreme rigidity.

OPERATION

All Type 210 switches are made for partial or full 360 degree rotation with 2 to 12 radial positions  Spring return switches are made for three positions but  can be furnished for a maximum of seven positions, three from either side of center position.  Maintained contact switches are available from 2 to 12 positions.   An increase in the number of positions decreases the travel between positions and reduces the interrupting capacity.

Circuit breaker control switches have a window in the position plate with a red and green flag indicator to show the last operation of the switch.  In the trip position, the signal lamp circuit can be opened by pulling the handle into the latch position.  The lamp is not lighted up when the handle is in this position, indicating that the circuit controlled by the breaker is not in use. Voltage control, speed control or motor control switches are not usually furnished with the flag indicator or pull-out feature.

The rotating contacts of standard 210 switches are mounted on a square insulated shaft.  Contacts may or may not be electrically insulated from each other, depending upon the desired circuit.  In operation, circuits are completed across various members of stationary contacts or a continuous circuit is maintained across two or more stationary fingers for a number of switch positions by mean of conductive spacers.  The stationary contact and positioning fingers are mounted on finger supports.  These in turn are mounted on a base of insulating material.  Contact pressure is provided by a spring.  External connections are made to the stationary contact finger through terminal studs below the base.

The positioning wheel, two roller arms and springs hold the shaft assembly in each position on maintained contact switches.  Mounted on the operating shaft, the star-shaped positioning wheel corresponds to the number of switch positions.  Spring action engages the roller arms by the notches in the positioning wheel.  This holds the switch in the desired position.  The switch also is designed to provide a spring return.

Because interrupting capacity depends on current, voltage and inductance of the circuit and speed of contact opening, control relays should be used with control switches on heavy currents.  These switches are made in standard construction for up to fourteen circuits.  In many cases additional circuits may be provided.

Standard 210 switch circuits are usually connected from a stud on one side of the terminal base through a segment of the shaft assembly to a stud on the other side.  This constitutes a single contact or stage.

A stage is a single-pole, double-break, single-throw contact.  In other switches involving various sequences and connections to the same circuit, the entire switch may serve as a single pole.

The operating shaft is made of 3/8-inch square, cold-rolled steel and rotates on brass bearings.  Extra thick end plates provide ample support for the shaft and base and assure permanent alignment of the contacts.  Movable contact segments are made of silver-plated brass.  The stationary contacts are made of heavy phosphor bronze and are silver plated.  This means low contact drop throughout the life of the switch even under conditions of oxidation or other corrosion . The rotating contacts are separated by high resistance insulators.

A square, linen-base phenolic insulation covers the shaft.  It is strong, high grade insulation and is impervious to humidity.  Spacers and contacts are held on the shaft by screw and lockwasher.  High compression springs give excellent contact pressure.  The contact construction utilizes a self-aligning, wiping action.  This assures clean, low resistance contact and means longer operating life. Copper shunts conduct the current from the contacts to the terminal studs.  The studs are mounted on the base block and are designed so they cannot come loose. Terminal base is made of molded, industry quality phenolic and has high mechanical and dielectric strength.  Each terminal base is numbered for identifying the connection from the wiring diagram. 

COMPONENTS

Handles . . . are made of a black molded composition in oval, round and pistol-grip shapes.  Colored handles available at a slightly higher price are blue, brown, grey, green, red, white, and yellow.  Instrument switches are normally furnished with round handles.  Voltage, motor and speed control switches come with oval handles, and circuit breaker control switches with the pistol grip.

Removable handles with a key shaft are available to prevent operation by unauthorized personnel or simultaneous operation of more than one switch controlling the same circuit.  They can be used with all instrument switches, although ammeter, regulator, transfer and temperature indicator switches are not normally key operated.

Synchronizing switches for synchronizing two machines require a removable handle for each machine.

Handles can be turned only in one direction.  Removable handles are labeled and constructed so that they can be inserted only in the proper switch or switches and then only in the “off” position.

Locks . . .  A lock can be mounted directly above the position plate of the switch.  The switch can be arranged to lock only in selected positions.

Position Plate . . . In addition to listed switches with proper titles and markings, position plates requiring special titles and markings can be supplied.

Face Dial Plate . . . The black position plate with its inscription is held in slots of the face plate.  In addition, the face plate serves as a holder for the flag indicator on control switches.

Shaft . . . 3/8-inch square, cold rolled steel is insulated with a covering of linen-base phenolic tubing.

Cover . . . The preventive cover is made of heat resistant, black, formed laminated phenolic.  This snap-on cover will not lose its springiness and is easily removed from the top, either side or by sliding off to the rear.

Contact Fingers . . . Heavy phospher bronze contact fingers are silver plated for long wear.  The contact pressure is about 12 ounces.

End Plates . . . Both end plates are 7/32 inches thick.  They are aluminum die cast to prevent corrosion.

Mill duty switches are heavy-duty control switches for use in steel mills, chemical plants, petroleum refineries and other industrial applications requiring constant and hard usage.  They are designed for 1/8 and 2-inch thick  panel mounting and are available with up to 14 stages (14 control circuits). 

Explosion-proof, water-tight and dust-tight enclosures can be furnished.

Ratings . . . Mill duty switches are rated for 10 ampere continuous duty.  Other ratings are identical to the standard 210 switches.

 

MIL SWITCH ADVANTAGES

Dependability . . .   Simple design and the use of heavy-duty, high grade components combine to give long trouble-free service under the most severe conditions.

Accessibility . . . Snap-on covers are quickly removed for easy access and inspection of contacts.  Terminal arrangement at the bottom of the switch permits wiring without removing the covers.  All terminals are clearly marked to identify connection from the wiring diagram.

Flexibility . . . Each pair of stationary contact fingers is mounted on a individually molded phenolic block.  Replacement or inspection of parts can be made at the installation.

 

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