RELAYS Panasonic

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Panasonic is part of a large worldwide groupselling relays and associated switching products under different brand names in different territories.The conditions of use in some territories may differ from those customary in Europe. In particular there are often major differences in regard to national and international specifications, such as UL, CSA, VDE, SEV, EVE, SEMKO, etc. Thus, when considering contact loads as stated in this catalogue (e.g. 10 A, 30 VDC for the SP relay) its hould be understood that these values are not necessarily an absolute maximum but tested ratings. Mostly the stated value has been tested for a certain life expectancy as stated by the manufacturer or the respective test house. Thus, under different conditions, the stated “maximum” may, in practice, be safely exceeded.

Vydal: Panasonic Electric Works Czech s.r.o. Autor: Panasonic

Strana 951 z 1090

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g. Refer them when selecting relay. an organic gas atm osphere, care required polym ers develop. Special characteristics are uniform thickness and the nonexistence pinholes. W hen these inductive loads are switched off, counter several hundred to several thousand volts develops which can severely damage contacts and greatly shorten life. xhibits low contact resistance, is inexpensive and idely used. Like silver, easily develops sulfide film sulfide atm osphere. The level reliability of these values depends switching frequency, bient conditions, change in the desired contact resistance, and the absolute value. Ag (silver) E lectrical conductivity and therm conductivity are the highest all etals. Surface Finish Au clad (gold clad) Au with its excellent corrosion resistance pressure elded onto base metal. Contact protection circuits and contact materials resistant material transfer such AgSnO AgW AgCu are used as countermeasures.1 0. This often occurs circuits where sparks are produced the moment the contacts “m ake” such when the current is large for inductive capacitive loads or when the inrush current large (several amperes several tens of amperes). Also, there are constraints processing and ounting contact springs. Therefore, the counter em exceeds this, discharge occurs the contacts dissipate the energy (1/2 Li2 ) stored the coil. Gold clad used prevent polym buildup. For this reason, is desirable absorb the counter so that 200V less. As the num ber switching operations increases, uneven contact surfaces develop such those shown Figure 13. • ria n Material transfer contacts occurs when one contact melts boils and the contact material transfers the other contact. AgPd (silver-palladium ) A standard tem perature, good corrosion resistance and good sulfidation resistance. Minimum applicable loads are given in the catalog; however, these are only provided guide the lower limit that the relay able switch and are not guaranteed values. Generally, a concave formation appears the cathode and convex form ation appears on the anode.General Application Guidelines limited resistive load, but there a broad meaning indicated for that class of relay, and ordinarily proper think of current capacity that for 125V AC circuits. However, a certain degree contact stability can obtained even when switching loads. 3 tio n • F W hen switching inductive loads with a DC relay such relay sequence circuits, DC motors, clutches, and DC solenoids, always important to absorb surges (e. the current these loads relatively small around or less, the counter will cause the ignition glow arc discharge. This may result contact failure. Please use relays with AgPd contacts when minute analog load control contact resistance higher than 100 desired (for easure­ ment and wireless applications, etc. fter while, the uneven contacts lock they were welded together. Excellent arc resistance.). Expensive.).5pm Purpose protect the contact base etal during storage the switch device ith built-in switch. are is required low voltage and low current levels. voltage meter (a) Several hundred to several thousand volts (b) Figure Example counter emf and actual measurement In Figure (a), counter di/ dt) with steep waveform generated across the coil with the polarity shown in Figure (b) the instant the inductive load switched off. disadvantage easily develops sulfide film sulfide atm osphere. Therefore, used herm etic sealed relays (reed relays, etc. with diode) to protect the contacts. A 2 (silver-tin) Exhibits superior elding resistance characteristics equal better than AgCdO . AgNi (silver-nickel) Equals the electrical conductivity silver. The counter f passes through the power supply line and reaches both contacts. The discharge decom poses organic atter contained the air and causes black deposits (oxides, carbides) develop on the contacts. For example, when the load either otor lamp, the extent the inrush current the tim of closing the circuit, ear the contacts, and the ount contact transfer increase, and contact welding and contact transfer make contact separation impossible. Au plating (gold plating) S ilar effect clad. • t The current both the closing and opening tim the contact circuit exerts important influence. For capacitive loads (several amperes several tens of 12 ds_x61_en_relay_technical_information_091112D ON OFF e :ü . reatly effective especially for low level loads under relatively adverse atm ospheres. Generally, the critical dielectric breakdown voltage standard tem perature and pressure air about 200 300 volts. Often difficult plem ent clad contacts existing relays due design and installation. Au flash plating (gold thin-film plating) 0. Expensive. Depending the plating process used, supervision portant there the possibility pinholes and cracks. Relatively easy plem ent gold plating existing relays. C ontact M aterial A gW (silver-tungsten) Hardness and elting point are high, arc resistance excellent, and highly resistant aterial transfer. plated contacts, used for relatively light loads. However, dry circuits, organic gases adhere and easily develops polym er. 2 tic ria ls Characteristics contact materials are given below. Furtherm ore, contact resistance relatively high and resistance to corrosion poor. Rh plating (rhodium ) C bines perfect corrosion resistance and hardness. However, high contact pressure required