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.
the current these
loads relatively small around or
less, the counter will cause the
ignition glow arc discharge. 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).
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. disadvantage easily develops sulfide film sulfide atm osphere. However, dry circuits,
organic gases adhere and easily develops polym er.
Au plating
(gold plating)
S ilar effect clad. Expensive. The
discharge decom poses organic atter
contained the air and causes black
deposits (oxides, carbides) develop on
the contacts. with diode) to
protect the contacts.
Ag
(silver)
E lectrical conductivity and therm conductivity are the highest all etals. Special characteristics are
uniform thickness and the nonexistence pinholes. fter while, the uneven contacts
lock they were welded together. an
organic gas atm osphere, care required polym ers develop. 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.
Contact protection circuits and contact
materials resistant material transfer
such AgSnO AgW AgCu are used
as countermeasures. As
the num ber switching operations
increases, uneven contact surfaces
develop such those shown Figure
13.
C ontact
M aterial
A gW
(silver-tungsten)
Hardness and elting point are high, arc resistance excellent, and highly resistant aterial transfer. are is
required low voltage and low current levels.
Like silver, easily develops sulfide film sulfide atm osphere. Depending the plating process used, supervision portant there the
possibility pinholes and cracks. xhibits low contact resistance, is
inexpensive and idely used.).
AgNi
(silver-nickel)
Equals the electrical conductivity silver.
• t
The current both the closing and
opening tim the contact circuit exerts
important influence. Please use relays with
AgPd contacts when minute analog load
control contact resistance higher
than 100 desired (for easure
ment and wireless applications, etc.
Au flash plating
(gold thin-film plating)
0.
However, high contact pressure required.1 0. Excellent arc resistance.
Generally, the critical dielectric
breakdown voltage standard
tem perature and pressure air about
200 300 volts.
Surface
Finish
Au clad
(gold clad)
Au with its excellent corrosion resistance pressure elded onto base metal.
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.g.). For this reason, is
desirable absorb the counter so
that 200V less. Also, there are constraints processing and ounting contact springs. However,
a certain degree contact stability can obtained even when switching loads.
Rh plating
(rhodium )
C bines perfect corrosion resistance and hardness. This may result contact
failure. For capacitive loads
(several amperes several tens of
12 ds_x61_en_relay_technical_information_091112D
ON OFF
e :ü
. The level reliability
of these values depends switching
frequency, bient conditions, change in
the desired contact resistance, and the
absolute value.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. Therefore, the counter
em exceeds this, discharge occurs the
contacts dissipate the energy (1/2 Li2 )
stored the coil. The counter f
passes through the power supply line and
reaches both contacts. Relatively easy plem ent gold plating existing relays. Therefore, used herm etic sealed
relays (reed relays, etc.
AgPd
(silver-palladium )
A standard tem perature, good corrosion resistance and good sulfidation resistance. plated contacts, used for relatively light loads. reatly effective especially for low level loads under relatively
adverse atm ospheres. Often difficult plem ent clad contacts existing relays due design and installation. Refer them when
selecting relay.
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. Generally, a
concave formation appears the
cathode and convex form ation appears
on the anode.
2 tic ria ls
Characteristics contact materials are
given below. Furtherm ore, contact resistance relatively high and resistance to
corrosion poor. Gold clad used prevent polym buildup. Expensive.5pm
Purpose protect the contact base etal during storage the switch device ith built-in switch.
A 2
(silver-tin)
Exhibits superior elding resistance characteristics equal better than AgCdO .
• ria n
Material transfer contacts occurs when
one contact melts boils and the contact
material transfers the other contact.
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
