Automotive Relay Glossary

Automotive Relay Glossary
The meaning of terms used in this catalog are stated below.
1 Coil
● Coil Symbol
● Coil Power Consumption
Coil drive types are displayed as below.
The power dissipated by the coil when the rated voltage is
applied to it. The coil power consumption is equal to the Rated
Coil Voltage multiplied by the Rated Coil Current.
mono -stable
● Pull In Voltage (Must Operate Voltage)
The minimum coil voltage required to pull-in the relay contacts at
a temperature of 20C.
● Drop Out Voltage (Release Voltage)
The minimum coil voltage at which a relay's contacts will dropout at a temperature of 20C.
● Rated Coil Voltage
A reference voltage applied to the coil when the relay is used
under the normal operating conditions.
● Rated Coil Current
The current which flows through the coil when the rated voltage
is applied at a temperature of 20C. The tolerance is +15C/
20C unless otherwise specified.
● Coil Resistance
The resistance of the coil, measured at a temperature of 20C. A
tolerance of ±10% shall apply unless otherwise noted.
● Hot Start
The Minimum Operate Voltage when measured immediately
following a pre-determined operating condition.
● Voltage Range
The region of safe operating potential applied to the coil.
● Maximum Continuous Coil Voltage
The voltage that can be continuously applied to the coil without
exceeding the maximum temperature limits.
2 Contacts
● Contact Form
● Contact Resistance
The contact mechanism of the relay.
Classification of the relay contact configuration. The most
common types in automotive applications are "A-Form" (SPST),
"B-Form" (SPST) and "C-Form" (SPDT).
The total electrical resistance of a pair of closed contacts
measured at their associated contact terminals. The contact
resistance values in this catalog are initial rated values; therefore
they are not an indicator of pass or fail after actual use in the
application circuitry.
Contact resistance is determined by measuring the voltage drop
across the contacts using the appropriate test current shown
● Contact Symbol
The symbol for each contact mechanism is displayed as below.
Contact symbol
in the catalog
Contact symbol
in the JIS
Note: JIS contact symbol is used in "Glossary: Terms related to relays" and
"Notice related to relays" except for special cases.
Contact Resistance =
Rated current or switched current (A)
1 or higher
: Ammeter
: Voltmeter
R : Variable resistor
Terminal Terminal
● Maximum Continuous Current Rating
The maximum wattage that can be switched without exceeding
the design parameters of the relay. Care should be taken to not
exceed this value. (VA is used in the case of AC. W is used in the
case of DC.)
Test current (mA)
0.1 or higher but less than 1
An expression of the voltage, current, or ambient temperature (or
any combination thereof) that a relay's contacts may be exposed
to while being expected to retain acceptable operating
● Maximum Switching Power
DC measurements are obtained by
testing with alternating polarities and
adopting the mean value.
Contact Resistance Test Current
● Contact Rating
The current that can be continuously carried through the
contacts without exceeding the maximum temperature limits.
Power source
(DC or AC)
● Maximum Contact Voltage
The maximum value of contact voltage that the contact can
withstand. Do not apply a voltage that exceeds the maximum
contact voltage of the relay.
● Maximum Switching Current (contact)
The maximum value of the contact current that the contact can
safely switch. Do not apply a current that exceeds the maximum
contact switching rating of the relay (this includes inrush.)
Automotive Relay Glossary
3 Electrical Characteristics
● Operate Time
● Bounce
The time that elapses between the instant power is applied to a
relay coil and the moment the contacts have closed. In case the
relay has several contacts, the duration of the operate time shall
be considered to end when the last contact has closed unless
otherwise specified. Release time is always specified at 20°C
unless otherwise noted. Operate bounce time is not included in
the operate time of a relay.
Intermittent opening and closing of contacts caused by vibration
or shock resulting from the collision of the relay's moving parts.
Operate Bounce Time
The time interval between the initial closure of the NO contact
and when the bounce ceases.
Release Bounce Time
The time interval between the initial closure of the NC contact
and when the bounce ceases.
Operate time
Release time
in the case of a
sole a-contact.
Release time
● Release Time
For an SPDT relay, the release time is the time that elapses
between the instant a relay coil is de-energized, and closure of
the NC contacts.
For an SPST relay, the release time concludes at the opening of
the NO contacts. Release time is specified at 20C unless
otherwise noted. Release bounce time is not included in the
release time of a relay.
● Insulation Resistance
The resistance between any two electrically conductive parts
within the relay that are intended to be electrically isolated from
each other.
Typical examples would include:
1. Between the coil and contact: Between the coil terminal and
all contact terminals
2. Between contacts of a different polarity: Between contact
terminals of a different polarity
3. Between contacts of the same polarity: Between contact
terminals of the same polarity
● Dielectric Strength
The ability of electrically isolated parts within the relay to
withstand high voltage applied across them without arcing.
Typically, an acceptable leakage current is established at a
particular voltage for a specified duration.
4 Mechanical Characteristics
● Vibration Resistance
● Shock Resistance
Vibration resistance of a relay is characterized by two values:
Shock Resistance of a relay is characterized by two values:
Malfunction Durability, refers to the maximum vibration the relay
can withstand without changing state (vibration doesn't cause
closed contacts to open or open contacts to close).
Malfunction Durability, refers to the maximum shock the relay can
withstand without changing state (vibration doesn't cause closed
contacts to open or open contacts to close.)
Mechanical Durability, refers to the maximum vibration the relay
can withstand without causing it to permanently change its
operating characteristics.
Mechanical Durability, refers to the maximum shock the relay can
withstand without causing it to permanently change its operating
5 Endurance (Lifetime)
● Mechanical Endurance (Lifetime)
● Minimum Carry or Switching Current
The number of operations the relay can successfully complete
without any electrical load.
The smallest acceptable value of carry or switching current that
maintains reliable electrical performance of the contacts.
● Electrical Endurance (Lifetime)
The number of operations the relay can successfully complete
with the rated load applied. Electrical endurance is not indicative
of relay performance for loads other than the rated load.
6 Ambient Temperature Range (When using, transporting and storing the relay)
The temperature limits under which the relay can predictably
operate are indicated on the data sheet. However, any freezing
condition is excluded.
This does not guaranteed to meet the values given on the data
sheet for the entire operating temperature range.
Automotive Relay Glossary
7 Contour and Shape
● Contour Dimension
Relay for automotive PCB
● Terminal Layout/Internal Connection
(1) Bottom View
For miniature relays, dimensions (either nominal or maximum)
are provided to aid the customer in the design process.
When a relay's terminals can not be seen from top view (such as
in the example below), the BOTTOM VIEW is shown in the
7.5 max.
7.2 typ.
14.3 max.
14.0 typ.
13.8 max.
13.5 typ.
2.5 min.
Soldering range
(2) Rotation direction to BOTTOM VIEW
1.2 +0.3
0.3 +0.3
The bottom view shown in the catalog or data sheet is rotated in
the direction indicated by the arrow, with the coil always on the
1.2 +0.3
0.6 +0.3
0.3 +0.3
Plug-in Relays
Maximum dimensions are shown as a reference for design.
● Marking
Various markings are used such as relay type, voltage rating,
internal connection diagram, etc. Because of space restrictions
on the surface of smaller relays, they may not display all of the
information found on larger relays.
● Mounting Orientation Mark
The top of all Omron relays are marked to indicate the location of
the relay coil. Knowing the terminal location aids in designing
PCB patterns, and when spacing components. Also, the printing
makes it easy to discern pin orientation when automatic or handmounting the relay.
Mounting orientation
PCB processing dimension
Terminal layout/Internal connection
Directional mark
Directional mark
Note: In a contour dimensional drawing, PCB process dimensional drawing or
terminal layout/internal connection diagram, the directional mark is found
on the left. JIS contact symbol is not inscribed to match with case
Axis of rotation
Safety Precautions for All Automotive Relays
Precautions for Safe Use
 This relay is intended for automotive use only. Do not subject it
to any other use. Refer to the specification and confirm that the
relay meets the application before using any relay from this
 Confirm acceptability for safety critical applications by
appropriate testing or contact Omron.
 Do not use the relay for loads which exceed the rated values
given in the data sheet. Failure to do so may result in
unforeseen consequences such as insulation failure, smoking,
breakdown of operation, etc.
 Do not apply over-voltage to the relay coil. Do not apply AC
power to a DC relay coil. Be careful not to exceed the
temperature ratings of the relay.
 Do not make incorrect connections to the relay terminals.
 Endurance (Lifetime) is significantly affected by changes to the
load and switching condition. When using the relay, check the
relay behavior with an actual product under actual conditions.
Use the relay within timing characteristics it can meet
according to the data sheet.
 Carry out the proper number of confirmation tests with an
actual product for each application or contact Omron.
 A relay is a precision part. Do not apply vibration and shock
beyond the specified value. Do not drop the relay. Do not use a
relay that has been dropped.
 Do not remove the case of a relay or modify the terminals in
any way.
 Do not touch the relay terminal or opposing mating terminal
while applying current. Electric shock may occur.
 Do not use a relay under any environment that contains
flammable or explosive gas. Fire or an explosion may result.
● When using a relay
 As with all technologies, relays may not always behave as
expected. Therefore, evaluation under actual application
conditions is always best.
 Each performance rating in this catalog is based on the value
under controlled conditions (i.e. temperature, humidity, etc 86
to 106kPa) unless otherwise specified. Confirm not only load
condition but also actual environmental conditions for actual
 Reference data in the catalog is based on measurement
values from sampling of production. The values are as
accurate as possible and believed to be correct at the time of
publication. Due to production necessity or other reasons,
specifications may change without notice.
 When a relay is used outside the recommended conditions,
there is no way for Omron to predict the failure mode or results
of the failure. Omron will remain blameless for the results of
applying relays outside of the recommended parameters
described in this catalog.
Safety Precautions
● Notice to ensure safety