Brochure
23
Technical Information – Relays
■
Latching Relays
Avoid use in locations subject to excessive magnetic particles or
dust.
Avoid use in magnetic fields (over 8,000 A.m).
Take measures to preventing problems caused by vibration or
shock. Problems may originate from other relay(s) operating or
releasing on the same panel.
Avoid simultaneous energization of the set and reset coils, even
though both coils can be continuously energized.
Avoid use under conditions where excessive surge-generating
sources exist in the coil power source.
When planning to mount multiple relays together, observe the
minimum mounting interval of each type of relay.
Drive Circuit (Double-winding Relays G5AK, G6AK, G6BK,
etc.)
When a DC-switching latching relay is used in one of the circuits
shown in the following diagram, the relay contacts may be
released from the locked state unless a diode (enclosed in the
dotted box in the circuit diagram) is connected to the circuit.
Circuits
When connecting a diode to the relay circuit, be sure to use a
diode with a repetitive peak–inverse voltage, and a DC reverse
voltage sufficient to withstand external noise or surge. Also be
sure that the diode has an average rectified current greater than
the coil current.
If the contact of the relay is used to de-energize the relay, the relay
may not operate normally. Avoid using the relay in a circuit like the
one shown below:
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PCB Design
Soldering
As demands for more compact electronic devices have grown, so
have demands declined for the plug-in relays that requires a bulky
socket for connection. This trend has lead to the development of
relays that can be soldered directly onto the PCB. Smaller relays
have made possible great density increases on the PCB, which in
turn reduces the size of the product or device. However, unless
the relay is fully sealed, when soldered onto a PCB, flux may
penetrate into the housing, adversely affecting the internal
circuitry.
The following points will help when designing a product which
uses relays. This section points out details to be noted when
soldering a relay to a PCB.
PCB Selection
In general, relays are directly mounted and soldered onto a PCB.
Although seemingly an uninvolved process, soldering and its
related processes of flux application, relay mounting, heat
application, and washing can be detrimental to a relay’s
performance. For example, if the PCB were to warp, the internal
mechanism of the relay could become distorted, degrading the
performance characteristics. Thus it could be said that the relay’s
characteristics are also affected by the size, thickness, and
material of the PCB. Therefore, carefully select a PCB that will not
jeopardise the performance of the relay.
PCB MATERIALS
Generally, the substrate of a PCB is made of glass epoxy (GE),
paper epoxy (PE), or paper phenol (PP). Of these, the glass-epoxy
or paper-epoxy PCB is recommended for mounting relays. See
the following table
XL: Latching relay
X
b: NC contact of relay
Load
Incorrect Use:
Xb
XL
Circuit connecting two reset coils in parallel.
(+)
(−)
S
1 S2 S3
SR SR
D
2
D1
K1 K2
Circuit connecting two set coils in parallel
(+)
(−)
S
1 S2 S3
SR
SR
D
1
K1 K2
D2
Circuit connecting set coil to reset coil.
(+)
(−)
K
1 K2
S1 S2 S3
SR
SR
D
2D1
Circuit connecting set coil of latching relay
in parallel with another relay coil.
(+)
(−)
S
1 S2 S4
SR
D
S
3
PCB Relays
Omron A5 Catalogue 2007 1-282 11/9/06 10:16 am Page 23