http://www.chiefent.com/products/M3_pop.asp PERFORMANCE Bosch's Micro 3 Relay offers an unusual blend of high performance and broad applicability to the commercial marketplace. Originally intended to meet the demands of safety applications, the relay was engineered to perform without failure at the most critical times or in the worst conditions - like when ABS is suddenly engaged. As its design evolved to meet the needs of multiple markets, the M3 retained its quality and performance. FLEXIBILITY The M3's flexible, cross-industry use is how its characteristics translate to bottom-line cost benefits. The latest in the Micro relay series, the M3 is an adaptation of the M2 platform but uses fewer parts. It features an ISO/DIN footprint and its drop-in installation/replacement design means that adoption to the M3 minimally impacts existing production processes. SAFETY Bosch has tested the M3 at length, and one of its notable advantages is switching 30 amps for over 100,000 cycles in an 85-degree Celsius ambient without failure. The STO (silver-tin- oxide) contacts offer high conductivity and are appropriate for a wide variety of applications. Such test ratings are proof of the M3's superior design characteristics and of its broad applicability. RELIABILITY Manufacturers of safety systems require its sheer reliability. Heavy industrial, marine, and construction applications choose it for its extreme environmental durability and ease of installation. Automotive manufacturers value being able to use a single part number in a variety of lighting and electrical systems. Check out the specifications of each of the M3 offerings. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> M3 - General Specifications Part Number: 0 332 011 007 Voltage: 12 V Form: SPST Enclosure: Standard cover Suppression: Resistor Contact Material: Silver Tin Oxide Life Tests Resistive Load - N/O: 30 A - 100,000 cycles Motor Load - N/O: 17 A (65 A In-rush) - 200,000 cycles Lamp Load - N/O: 17 A - 150,000 cycles Mechanical Life: 1000000 Coil Specifications Coil Operating Current: 160 mA Equivalent Coil Resistance: 75 +/- 6 ohm Pull-in Voltage: <= 8.0 V Drop-out Voltage: => 1.5 V Operating Conditions Operating Temperature: -40 C to +100 C Humidity Test: n/a Salt Spray Test: 48 hours Dust Test: n/a >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> http://www.leachintl2.com/english/english2/vol6/properties/faq.html 7. What is the difference between resistive, inductive, motor, and lamp loads? We must express the load as a contact rating, which is the electrical load-handling capability of relay contacts under specified conditions and for a prescribed number of operations or life cycles. RESISTIVE LOAD: A resistive load usually consists of some sort of resistance in the circuit; e.g., heaters, resistors, etc. INDUCTIVE LOAD: An inductive load consists of a load created by a wire wound coil, such as in a relay or solenoid, a transformer, or any load which uses a winding over a magnetic iron core. Breaking an inductive load is usually more severe than breaking a resistive load and will generally produce heavy arcing. MOTOR LOAD: A motor load can be referred to as a rotating inductive load, generally with a high inrush of six times the normal load. The breaking of the load is much the same as a resistive load. LAMP LOAD: There are many types of lamp loads such as tungsten filament, fluorescent, mercury-vapor, and other exotic gas lamps. The loads we normally concern ourselves with are tungsten filament. Tungsten filament lamps, when first turned on, will draw an inrush current of 10-15 times of the steady-state current. The inrush is similar to a motor load inrush and is caused by the cold filament in the lamp. After the lamp filament has heated up, the current will drop to its normal level. Most tungsten filament lamp load ratings are 20% of a resistive load. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> SUPRESSION Need diode? A diode may be installed across (in parallel with) the contacts (load) to prolong life if you have an inductive load (think "magnet" ) or in series with the coil (control) to convert AC signal to DC (not an issue with automotive applications), or across (parallel) with the coil to protect whatever is controlling the relay, only an issue if you are controlling with a very sensitive transistor or such. Diodes are used to prevent damage from what is commonly called "inductive kick". This happens whenever you try to instantly stop current that is going through an inductive load. This causes a very high voltage. The diode is actually a Zener diode, and will "turn on" at a specific voltage to shunt the energy to ground. These could be used on either the input (the relay coil is an inductor) or the output (for a fan motor or fuel pump). Need resistor? Resistors might be used on the input if the coil resistance is very low and it is intended to be used with a 12V system. This will prevent the coil from overheating. A resistor might be used on the output to prevent damage due to inrush current for something like a motor. However, this means that the resistor is constantly dissipating power, and that might not be a good thing depending on location, use, etc. ... When you disconnect or turn off parallel-connected inductive loads, such as fuel pumps, relays, horns, solenoids, and starter motors, they can generate negative-voltage transients as great as ? 100V on the power rail.