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.
Typical contact protection circuits
are given the table below.) the
immediate vicinity the load contact.
(G: Good, NG: Good, Conditional)
Circuit
Application
AC DC
Features/Others Devices Selection
CR circuit
If the load timer, leakage current flows
through the circuit causing faulty
operation.
Although extremely effective arc suppression
as the contacts open, the contacts are
susceptible welding since charging current
flows “C” when the contacts close. Capacitor “c” acts to
suppress the discharge the moment the
contacts open.
* used with voltage, sure the
impedance the load sufficiently
smaller than that the circuit
If the load relay solenoid, the
release time lengthens.
No good -
Contact
_ Power 'S
' supply o
T
No good -
Contact
_ Power -
' supply C
TJ
L to
- o
J r
Although extremely effective arc suppression
as the contacts open, the contacts are
susceptible welding since energy stored in
“C” when the contacts open and short-circuit
current flows from “C” when the contacts close.
Varistor circuit
Using the stable voltage characteristics of
the varistor, this circuit prevents
excessively high voltages from being
applied across the contacts.
C tio Use contact protective devices or
protection circuits can suppress the
counter low level.
Diode circuit NG
The diode connected parallel causes
the energy stored the coil flow the
coil the form current and dissipates it
as joule heat the resistance component
of the inductive load.
Contact
G
Contact
Contact
G
Contact
G
Contact
G G
• Avoid using the protection circuits shown
in the figures the right. This circuit
also slightly delays the release time.General Application Guidelines
amperes), always necessary to
conduct actual confirmation tests.
Diode and
zener diode
circuit
NG
Effective when the release time the
diode circuit too long. Use capacitor
“c” with breakdown voltage 200 to
300V. times the release time
listed the catalog)
Use diode with reverse breakdown
voltage least times the circuit voltage
and forward current least large as
the load current. electronic circuits
where the circuit voltages are not high,
a diode can used with reverse
breakdown voltage about times
the power supply voltage.
Although inductive loads are usually
more difficult switch than resistive
loads, use the proper protection circuit
will raise the characteristics that for
resistive loads. Use type capacitors (non
polarized) for circuits.
ds_x61_en_relay_technical_information_091112D 13
. Resistor “r” acts limit the
current when the power turned the
next time.
• h
fr itc s
( tio )
If, for example, valve clutch is
switched high frequency, blue-
green corrosion may develop. This
occurs from the reaction with nitrogen
and oxygen the air when sparks (arc
discharge) are generated during
switching. Effective when
connected both contacts the power
supply voltage 48V and the
voltage across the load 100 200V. Therefore, care required in
circuits where sparks are generated a
high frequency. This circuit further
delays the release time compared the
CR circuit. Test confirm.5 per contact voltage
Values vary depending the properties
of the load and variations relay
characteristics.
If located too far away, the effectiveness
of the protective device may diminish. However, note
that incorrect use will result adverse
effect.
As guide selecting and r,
c: 0.
Effective when connected both contacts
if the power supply voltage 48V
and the voltage across the load 100 to
200V.
• tin tiv e
In the actual circuit, necessary to
locate the protective device (diode,
resistor, capacitor, varistor, etc.5 1pF per contact current
r: 0. As
a guide, the distance should within
50cm.
Use zener diode with zener voltage
about the same the power supply
voltage
