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