From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Product brochure detailing the mechanical and electrical characteristics of the Burgess Micro Switch.
| Identifier | ExFiles\Box 152\3\ scan0180 | |
| Date | 1st January 1934 guessed | |
| BERYLLIUM COPPER PROVIDES NEW SWITCH CHARACTERISTICS MECHANICAL CHARACTERISTICS MOTION REQUIRED THE Burgess Micro Switch is designed to operate with a snap action when the actuating plunger is depressed to a given point, and to return with a snap to its normal position when the plunger is allowed to return .001" toward its normal position. PRESSURE REQUIRED A PRESSURE of approximately 14 ounces is required to actuate the Burgess Micro Switch, but upon subsequently releasing the pressure, the switch lever will return with a snap to its normal position when the pressure is reduced to approximately 10 ounces. Thus the pressure differential required to operate is only approximately 4 ounces. Preloading is recommended only in the case of relatively light loads. It is obvious that in certain applications in which less force than 4 ounces and more motion than .001" are available, a lever can be used to obtain the desired results. For determining the adaptability of the Burgess Micro Switch it is useful to remember that only four one-thousandths of an inch-ounce of energy is required to operate it. OVERLOADING THE plunger which operates the Micro Switch is of metal with a sturdy molded glass button head, and is so designed as to bear against a positive stop before damage can be done to the operating spring. It will withstand 50 pounds steady pressure, or impact from a 1 pound weight dropped 1 1/2 inches. OPERATES IN ANY POSITION ONE of the most useful features of the Burgess Micro Switch is that the operating parts are not affected by gravity or vibrations; consequently the switch can be used in any position and can be mounted on vibrating machinery, motors, etc. without interfering with its positive, accurate performance. SPEED EFFECTIVE use of the Burgess Micro Switch can be made in equipment requiring relatively rapid action. At its rated current capacity, the switch can be operated up to 60 times per minute. Higher speeds are possible in applications involving smaller currents, as follows: Voltage | Current (non-inductive load) | Maximum Speed 110 AC | 1 ampere | 10 operations per second 220 AC | 1/2 ampere | 10 operations per second 440 AC | 1/4 ampere | 10 operations per second EASY TO MOUNT THE mounting of the Burgess Micro Switch is extremely simple, only two No. 6 screws, one inch long, or their equivalent, being required. As there are no overhanging projections, the switch can be mounted flush with any flat surface. The mounting holes, as well as the operating plunger, are fully insulated from the electrical circuit. BIG SILVER CONTACTS THE accompanying sketch shows the actual size of the silver contact on the moving arm. The generous use of silver on both contacts assists in the dissipation of heat and is one of the reasons for the large capacity of the switch. FLEXURES CORRECT design plus the remarkable physical properties of beryllium copper assure long life. In high speed applications, where a life in excess of 1,000,000 operations is required, travel of the actuating mechanism should be limited so that the Micro Switch plunger will not be depressed more than .005" beyond the point at which it operates the switch. RUGGEDNESS THE body and cover are of ample thickness molded Bakelite and the internal parts are light and rigidly mounted. The elimination of thin walled glass and loose, heavy materials characteristic of other types of switches reduces the breakage problem to a minimum. MOUNTING DIMENSIONS FEATURES - Compactness - Large silver contacts - High overload capacity - Freedom from effects of vibration - Low contact resistance, high current capacity - Operation on .001" motion - Rugged, completely insulated housing - Positive snap action, whether operated fast as on a vibrator, or slow as on a thermostat - Sealed, dust proof construction—a guarantee against tampering in service and failures from dirt. ELECTRICAL CHARACTERISTICS INDUCTIVE LOADS FOR inductive loads, such as motors, solenoids, or transformers, the Burgess Micro Switch will safely make and break the following circuits: - 10 amperes at 110 volts AC - 5 amperes at 220 volts AC - 2 amperes at 440 volts AC - 1/2 horsepower motor, 110 or 220 volts AC On normally open contacts, motor starting current should generally be limited to 20 amperes. Overload capacity is such that in an emergency the Micro Switch will carry indefinitely a current of 30 amperes—the full stalled rotor current of a 1/2 h.p. motor, and break the circuit safely if called upon to do so. HEATER LOADS IN controlling pure resistance loads, such as electrical heating coils for domestic or industrial appliances, the Burgess Micro Switch will perform satisfactorily in continuous service controlling the following: - 10 amperes at 110 volts AC - 5 amperes at 220 volts AC - 2 amperes at 440 volts AC This switch lends itself admirably to thermostatic control of electrical heating devices, electric ovens, and other equipment requiring precision temperature control. LAMP LOADS LAMP loads differ from pure resistance loads only in the high instantaneous inrush current which occurs before the lamp filaments become incandescent. Normally closed contacts of the Micro Switch will handle 1,000 watts lamp load at 110 or 220 volts AC. Normally open contacts should be limited to 3 ampere lamp loads at 110 or 220 volts AC. For electric sign flasher applications, the Burgess Micro Switch offers many startling possibilities. DIRECT CURRENT APPLICATIONS SUCCESSFUL performance can be obtained in direct current applications where relatively small currents or voltages are concerned, and proper condenser protection is afforded; but because of the interdependence of voltage, current, inductance and protective condenser values, each application must be studied separately. The following may serve as a guide to approximate current handling capacity: Voltage | Maximum Current Load | Condenser Shunt Recommended 110 DC | 3 amperes non-inductive | 1 Microfarad* 110 DC | 1 ampere inductive | 1 Microfarad* 220 DC | 1 1/2 amperes non inductive | 1 Microfarad* 220 DC | 1/2 ampere inductive | 1 Microfarad* 6 DC | 20 amperes non-inductive | 1/4 Microfarad 6 DC | 10 amperes inductive | 1 Microfarad *A resistance of from 1/2 to 1 ohm should be placed in series with condenser on the Green Top and on normally open contacts of the Blue Top type. Slightly heavier loads may be controlled using a larger capacity condenser. For inductive loads the condenser should have a voltage rating of from three to ten times the circuit voltage, depending upon the current and inductance. Types Available The Burgess Micro Switch is furnished in the three following standard types: Red Top, Single throw, normally closed ... List $1.00 Green Top, Single throw, normally open ... 1.00 Blue Top, Double throw ... 1.20 Standard Package: Ten of any single type. 10% discount. For special problems where it is necessary to have slightly modified characteristics—such as a split contact switch, or one which remains operated until manually reset—other types of Micro Switches can often be furnished. Inquiries regarding special applications are welcome; Burgess engineers are equipped to analyze these problems and will gladly make recommendations. | ||