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Solenoid Technical Information

Solenoid Technical Information
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1. Introduction A large number of application possibilities, simple design and long service life make Penny+Giles solenoids cost-effective solutions for the most selected problems. Applications range from general machine construction through plant engineering, vehicle construction, robotics, precision mechanics, household appliances and medical technology to hydraulic and pneumatic controls. High reliability, long service life and high efficiency are all requirements that are met by Penny+Giles solenoids through precision manufacture, tight tolerances and suitable surface treatment. Customer-related solutions are developed in conjunction with the customer. 2. Operation Solenoids transform electrical energy into mechanical movement. 3. Direct Current (DC) Solenoids Contrary to an alternating current (AC) solenoid, the power consumption of a direct current (DC) solenoid is independent of the position of the plunger. DC solenoids are also characterised by soft and hard operation. Inherently longer cycling times can be reduced by special circuitry. It is also possible to modify the stroke-force characteristics. High switching frequencies do not cause dangerously high thermal loads in DC solenoids; the maximum switching frequency is only limited by the pull-in and drop-out times. 4. Alternating Current (AC ) Solenoids Unlike DC solenoids, AC solenoids provide relatively high operating/cycling frequencies and low cycling times; this results in hard operation which influences service life. Power consumption depends on the position of the plunger. High cycling frequencies can cause dangerously high thermal loading in AC solenoids and the maximum permissible temperature is therefore the limiting factor for cycling frequency. 5. Force Usually, the correct solenoid for a given application is the smallest one that has adequate magnetic force. 5.1. Magnetic force The magnetic force in Newtons is the usable portion (i.e. that portion which is reduced by friction) of the mechanical force that is produced by the solenoid. It is measured at 90% of the rated voltage at normal operating temperature. 5.2. Holding force The holding force of a solenoid is the force that is effective at the end of the stroke. 5.3. Residual force The residual force, generated by any remaining (residual) magnetism, is the holding force that still applies after the electrical power is stopped. This force can be influenced by design features. 5.4. Return force The return force is the force required to return the plunger from the end of stroke to the start of stroke. 5.5. Magnetic force / stroke characteristic Traditional curves indicate the plunger movement toward the final (energised) position. 6. Stroke The stroke is the usable distance travelled by the plunger from its initial position to the end of travel. As the stroke is increased the force is reduced and vice versa. 6.1. Start of Stroke This is the position of the plunger before it starts its travel. It is also the position when it returns upon conclusion of the complete cycle. 6.2. End of Stroke This is the designed final position of the plunger upon conclusion of the work portion of the complete cycle. 6.3. Stroke work For the linear solenoid, the stroke work (in Newtons) is the magnetic force over the magnetic stroke. A solenoid is the correct size if the magnetic force exceeds the opposing force at all times with only a slight amount of excess force to ensure long service life. A solenoid is too small if the magnetic force is less than the opposing force over a certain range. 7. Time terms The use of solenoids necessitates a certain chronological sequence best clarified with the following terms: 7.1. Power-off pause The power-off pause (in seconds) is the time between switching off the current and switching it on again. 7.2. ON period This is the period (in seconds) between switching the current on and off again. 7.3. Cycle period This is the sum of the ON period and the Poweroff pause. 7.4. Duty cycle The ratio between the ON and the cycle period is the relative ON period in %. 7.5. Cycling sequence The cycling sequence (in seconds) is the single or periodically repeated joining of cycle period values of very different durations. 7.6. Response time The response delay (in seconds) is the time between application of the current and initial movement of the plunger. 7.7. Stroke time This time (in seconds) starts when the plunger begins to move from its initial position and ends when it reaches its limit of travel. 7.8. Pull-in time The sum of Response time and Stroke time is the time required by the plunger to perform its work. Special measures in the circuit can shorten the pull-in time. 7.9. Drop-out delay Drop-out delay (in seconds) is the time from current cut-out until the plunger starts to return to its initial position. 7.10. Return time The return time (in seconds) is the time from the beginning of plunger return motion until it has reached its initial position. 7.11. Drop-out time The sum of Drop-out delay and Return time is the drop-out time (in seconds). Thrust Rod Bearing Plunger Circlip Spring Flux Plate Terminals or Leads Bearing Pin Connectors Connector Housing Coil Assembly Encapsulated or Taped Finish Frame Stop Thrust Cap Washer Anti Residual Or Anti Impact Solenoid Technical Information

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Penny+Giles Controls Ltd Unit 50, Innovation House, South Church Enterprise Park Bishop Auckland, County Durham DL14 6XB Tel: +44 (0) 1388 771200 Fax: +44 (0) 1388 772490 solenoids@pennyandgiles.com www.pennyandgiles.com © Penny+Giles Controls Ltd 2011 8. Temperature terms and class es of insulating material When selecting a suitable solenoid, temperature must be considered. 8.1. Ambient temperature The ambient temperature is the temperature (°C) surrounding the solenoid when it is operating. If the range is outside +40°C to -50°C design changes may be required. 8.2. Permanent operating...

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