7
1. Driving Circuit for Relays
1. To make sure of correct relay operation, apply
rated voltage to the relay coil. Pickup and dropout
voltages may differ according to operating
temperature and conditions.
2. Input voltage for DC coil:
A 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 rectications 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
Capacitor
Emin Emax Emean
DC
Ripple Factor (%
100%
Emax –
Emin
Emax = Maximum of pulsating current
Emin = Minimum of pulsating current
Emean
3. Operating the relay in sync with an AC load:
R
in
E
Load
in
AC
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:
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) ows 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.
Incorrect
R
I0
Correct
R
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, or
use RF1V with counter-electromotive force diode.
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
suppressing diode
Rela
+
–
6. The coil terminal of the relay has polarity. Connect
terminals according to the internal connection
diagram. Incorrect wiring may cause malfunction.
2. Protection for Relay Contacts
1. The contact ratings show maximum values.
Make sure that these values are not exceeded
even momentarily. When an inrush current ows
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 an
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
wer CR Ind.
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
C
R
wer Ind. Load
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
D
wer Ind.
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
Varistor
wer Ind. Load
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:
Power
CLoad
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.
CLoad
Power
This protection circuit is very effective in
arc suppression when opening the contacts.
But, when the contacts are closed, a current
ows to charge the capacitor, causing contact
welding.
Generally, switching a DC inductive load is more difcult
than switching a DC resistive load. Using an appropriate arc
suppressor will improve the switching characteristics of a DC
inductive load.
3. Usage, transport, and storage conditions
1. Temperature, humidity, atmospheric pressure
during usage, transport, and storage.
➀ Temperature: –40°C to +85°C (no freezing)
See page 4 for the current and operating
temperature.
➁ Humidity: 5 to 85%RH (no condensation)
The humidity range varies with temperature. Use
within the range indicated in the chart below.
➂ Atmospheric pressure: 86 to 106 kPa
Operating temperature and humidity range
Tolerance Range
(Avoid freezing
when using at
temperatures
below 0ºC)
(Avoid
condensation
when using at
temperatures
above 0ºC)
85
5
0–40 85
Humidity (%RH)
Temperature (ºC)
2. Condensation
Condensation occurs when there is a sudden
change in temperature under high temperature
and high humidity conditions. The relay insulation
may deteriorate due to condensation.
3. Freezing
Condensation or other moisture may freeze on the
relay when the temperatures is lower than 0ºC.
This causes problems such as sticking of movable
parts or delay in operation.
4. Low temperature, low humidity environments
Plastic parts may become brittle when used in low
temperature and low humidity environments.
4. Panel Mounting
When mounting DIN rail mount sockets on a panel,
take the following into consideration.
•Use M3.5 screws, spring washers, and hex nuts.
•For mounting hole layout, see dimensions on page
6.
•Keep the tightening torque within 0.49 to 0.68 N·m.
Excessive tightening may cause damage to the
socket.
5. Others
1. General notice
➀ To maintain the initial characteristics, do not drop
or shock the relay.
➁ The relay cover cannot be removed from the base
during normal operation. To maintain the initial
characteristics, do not remove the relay cover.
➂ Use the relay in environments free from
condensation, dust, sulfur dioxide (SO2), and
hydrogen sulde (H2S).
➃ The RF1V relay cannot be washed as it is not a
sealed type. Also make sure that ux does not leak
to the PC board and enter the relay.
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.
➀ Connect an integration circuit.
➁ 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
eld, as this may affect relay operation.
4. UL and CSA ratings may differ from product rated
values determined by IDEC.
Operating Instructions
RF1V Force Guided Relays/SF1V Relay Sockets