159
R
B) No damage will occur to the coil of
either the one or two coil bistable types
even if the operating voltage is as much
as 2 or 3 times the nominal coil voltage.
C) If separate pulses are applied to each
coil of the 2 coil bistable types, the first
pulse will operate when the pulses are of
equal voltage. When voltages differ the
higher voltage will cause operation
provided the voltage difference is greater
than the measured pick-up voltage.
Voltage difference on the coils will
reduce contact pressure proportionately.
Continuous bias voltage after an
operating pulse lowers contact pressure
and vibration resistance.
Ripple factor
Coils should be operated on pure DC.
Rectified AC may cause changes in the
pick-up/drop-out characteristics because
of the ripple factor. Use of a capacitor in
the circuit is recommended to keep the
ripple factor below 5%.
: relay
E min. E max. E mean DC component
Pulsating component
capacitor (ripple filter)
R
R
To calculate the ripple factor
Ripple factor (%) = × 100%
E max. = max. value of pulsating component
E min. = min. value of pulsating component
E mean - average value DC component
E max. – E min.
E mean
When designing R relay circuits
Care should be taken when designing
relay circuits since the response of the
relay is so fast that bouncing or
chattering from conventional relays in the
circuit may cause false operation.
When using long lead wires
When long wires (as long as 100 m or
more) are to be used, the use of
resistance (10 to 50 Ω) in series with the
contact is required in order to eliminate
the effect of the possible inrush current
due to the stray capacitance existing
between the two wires or between the
wire and ground.
Contact of R relay
Lead wire
+
Energy accumulated in
static capacitance
(100 to 300 m)
10 to 50 Ω
(Equivalent circuit)
AC operation of latching relays
When using circuits such as those at the
right, avoid continued or extended
latching or resetting power input.
Latching
switch
1 coil bistable type
Reset
switch
Latching
switch
2 coil bistable type
Reset
switch
2
5
36
Capacitor discharge operation of latching types
When operating bistable (latching) types
by discharge of a capacitor, more reliable
operation can be expected if the time to
reach pick-up voltage is greater than 2
ms at 5 to 10 µF: (24 V type).
R relay
coil
Specified
Pick-up voltage
more than 2 ms
t
(V)
SW
C
