When selecting a switch for your specific application, we suggest you identify all your requirements and then use the information to determine the best OTTO switch for your need. Our Applications Engineers are here to help you determine your requirements, and some parameters to consider follow here.

RATINGS
Stated ratings of a switch are expressed in various values depending on load, voltage, contact size, material, life, etc. For example, the OTTO P1 is rated 10 amperes when the load is resistive and the voltage is 115 VAC or 28 VDC. Exhaustive tests run at these conditions consistently yield well over the required 25,000 cycles life. When switching lower ampere loads, the electrical life can be expected to increase. As the switching load approaches the milliampere region, the electrical life can be expected to approach the mechanical life.

LOADS
Resistive
Heating and other pure resistive loads are the easiest to switch. Power factors are high and contact life is maximized because contact erosion is minimized.

Inductive
Probably the most troublesome of circuit conditions, inductive type loads cause premature contact erosion if not handled properly. Inductance in a circuit retards current flow upon contact closure. Upon opening, current tends to keep flowing across the contact, causing arcing. Suppressors consisting of an R-C (Resistor & Capacitor) for alternating current or a diode for direct current are recommended for severe duty.

Tungsten (Lamp)
Inrush current is the condition to watch. Lamps are rated based on resistance when the lamp is hot. However when the lamp is cold, the resistance is low. Inrush current can be 10 to 15 times normal current. OTTO double-break switches greatly improve contact life under lamp conditions due to the wiping action inherent in the double-break design that helps break welds.

CONTACTS
Resistance
Low contact resistance is important in low level circuits. OTTO designs consistently produce less than 25 milliohms resistance through the life of the switch. High contact pressure and good wiping action are among the reasons behind this excellent rating.

Materials
Size, in combination with materials and shape, helps to determine contact handling ability. Silver contact material is the most prevalent because of its excellent conductivity and low electrical resistance. Solid gold or diffused gold contacts are used normally for low level switching and where long shelf life is required. Rhodium and some other exotic materials are also available for special conditions.

Bounce
When hard contacts come together, they rebound. Contact mass, forces and frequency of supporting members are all components that determine the extent of bounce. Total transfer time consists of the time for the contacts to close plus bounce. Transfer time should be rapid so natural bounce time is short. OTTO switches exhibit extremely quick closure time, and therefore behave well even under tungsten loads.

Contact Pressure
High contact pressure between closed contacts helps to lower the contact resistance. High contact pressure results in reduced heating, ease of surface film breakthrough, and better resistance to vibration. Many OTTO switches feature contact pressure in the 120 gram region.

Single vs. Double-Break
Double-break switches are generally capable of interrupting higher electrical loads over a longer life cycle. Double-break switches break the circuit at two points simultaneously. The contact gap opens twice as fast, thus reducing the arc duration, contact surface temperature and material erosion. The overall result is longer life of the contacts. Single-break switches have only one contact gap. All the energy from the arc is concentrated on the single contact.