Instructions
RJ Series Slim Power Relay (bifurcated contacts)
1. Driving Circuit for Relays
1. To make sure of correct relay operation, apply
rated voltage to the relay coil.
2. Input voltage for DC coil:
Complete DC voltage is best for the coil power
to make sure of stable operation. When using
a power supply containing a ripple voltage,
suppress the ripple factor within 5%. When
power is supplied through a rectification circuit,
relay operating characteristics, such as pickup
voltage and dropout voltage, depend on the
ripple factor. Connect a smoothing capacitor for
better operating characteristics as shown below.
+
–R
Smoothing
Capacitor
Relay
Pulsation
Emin Emax Emean
DC
Ripple Factor (%) ×100%
Emax – Emin
Emax = Maximum of pulsating current
Emin = Minimum of pulsating current
Emean = DC mean value
Emean
3. Operating the relay in sync with an AC load:
If the relay operates in sync with AC power
voltage of the load, the relay life may be reduced.
If this is the case, select a relay in consideration
of the required reliability for the load. Or, make
the relay turn on and off irrespective of the AC
power phase or near the point where the AC
phase crosses zero voltage.
4. Leakage current while relay is off:
Incorrect
Correct
When driving an element at the same time as
the relay operation, special consideration is
needed for the circuit design. As shown in the
incorrect circuit below, leakage current (Io)
flows through the relay coil while the relay is off.
Leakage current causes coil release failure or
adversely affects the vibration resistance and
shock resistance. Design a circuit as shown in
the correct example.
5. Surge suppression for transistor driving circuits:
When the relay coil is turned off, a high-voltage
pulse is generated. Be sure to connect a diode
to suppress the counter electromotive force.
Then, the coil release time becomes slightly
longer. To shorten the coil release time, connect
a Zener diode between the collector and emitter
of the controlling transistor. Select a Zener
diode with a Zener voltage slightly higher than
the power voltage.
R
Counter emf
suppressing diode
Relay
+
–
2. Protection for Relay Contacts
1. The contact ratings show maximum values.
Make sure that these values are not exceeded.
When an inrush current flows through the load,
the contact may become welded. If this is the
case, connect a contact protection circuit, such
as a current limiting resistor.
2. Contact protection circuit:
When switching an inductive load, arcing
causes carbides to form on the contacts,
resulting in increased contact resistance. In
consideration of contact reliability, contact
life, and noise suppression, use of a surge
absorbing circuit is recommended. Note that the
release time of the load becomes slightly longer.
Check the operation using an actual load.
Incorrect use of a contact protection circuit will
adversely affect switching characteristics. Four
typical examples of contact protection circuits
are shown in the following table:
RC
This protection circuit can be
used when the load impedance
is smaller than the RC
impedance in an AC load power
circuit.
R: Resistor of approximately
the same resistance value as
the load
C: 0.1 to 1 µF
This protection circuit can be
used for both AC and DC load
power circuits.
R: Resistor of approximately
the same resistance value as
the load
C: 0.1 to 1 µF
Diode
This protection circuit can be
used for DC load power circuits.
Use a diode with the following
ratings.
Reverse withstand voltage:
Power voltage of the load
circuit × 10
Forward current:
More than the load current
Varistor
This protection circuit can be
used for both AC and DC load
power circuits.
For a best result, when using
on a power voltage of 24 to
48V AC/DC, connect a varistor
across the load. When using
on a power voltage of 100 to
240V AC/DC, connect a varistor
across the contacts.
3. Do not use a contact protection circuit as shown
below:
This protection circuit is very effective in arc
suppression when opening the contacts. But,
the capacitor is charged while the contacts
are opened. When the contacts are closed,
the capacitor is discharged through the
contacts, increasing the possibility of contact
welding.
This protection circuit is very effective in arc
suppression when opening the contacts.
But, when the contacts are closed, a current
flows to charge the capacitor, causing contact
welding.
Generally, switching a DC inductive load is more difficult
than switching a DC resistive load. Using an appropriate
arc suppressor will improve the switching characteristics of
a DC inductive load.
3. Notes on PC Board Mounting
When mounting 2 or more relays on a PC board,•
keep a minimum spacing of 5 mm in each
direction.
Manual soldering: Solder the terminals at 350°C•
within 3 sec., using a soldering iron of 60W (Sn-
Ag-Cu type) is recommended.
Auto-soldering: Solder at•
250°C within 4 to 5 sec.
Because the terminal part is filled with epoxy•
resin, do not excessively solder or bend the
terminal. Otherwise, air tightness will degrade.
Avoid the soldering iron from touching the relay•
cover or the epoxy filled terminal part.
Use a non-corrosive resin flux.•
4. Others
1. General notice:
To maintain the initial characteristics, do not•
drop or shock the relay.
The relay cover cannot be removed from the•
base during normal operation. To maintain
the initial characteristics, do not remove the
relay cover.
Use the relay in environments free from dust,•
sulfur dioxide (SO2), hydrogen sulfide (H2S),
or organic gases.
Make sure that the coil voltage does not•
exceed the applicable coil voltage range.
2. Connecting outputs to electronic circuits:
When the output is connected to a load which
responds very quickly, such as an electronic
circuit, contact bouncing causes incorrect
operation of the load. Take the following
measures into consideration.
a. Connect an integration circuit.
b. Suppress the pulse voltage due to bouncing
within the noise margin of the load.
3. Do not use relays in the vicinity of strong
magnetic fields, as this may affect relay
operation.
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Specifications and other descriptions in this catalog are subject to change without notice.
Cat. No. EP1376-0 JUNE 2011 PDF
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