Load
+
Load
+
OFF
Load
+
Ａ
B
B side OFF
Load
+
Short current
Arcing
Arcing
5
Connect the load to one side of the power supply as shown in Fig. (a). Connect the contacts to the other
side. This prevents high voltages from developing between contacts. If contacts are connected to both
side of the power supply as shown in Fig. (b), there is a risk of shorting of the power supply when
relatively close contacts short.
Fig. (a) Good example (b) Bad example
23. Connection
of load
Regarding the following circuit constructions with 2-coil relays (twin relays) or single-pole relays, an arc
between contacts may be generated when breaking of load current depending on the type of load
current, voltage, and load. Please note that or contact us.
＜
2 coil relay (twin relay) or two of single-pole relays
＞
＜
Single-pole relay
＞
4. Load,
electrical
life
24. Short
between
interelectrodes
When using of multipole relays such as 2-coil relays (twin relays), verify insulation and breakdown
voltage between contacts in each pole in order to avoid an accident caused by short.
After continuous applying of current to coil and contacts, if the current is turned OFF then immediately
turned ON again, coil resistance and the pick-up voltage will increase due to the temperature rise in the
coil.
1. Hot start
voltage
Temperature rise value of coil is greatly affected by circuit board, connected harness, connected
connector, heat dissipation of system/modules, and heat source around relay. Please verify whether it is
operating properly or inoperative under actual vehicle and actual use conditions.
Coil resistance and the pick-up voltage will increase when the relay is used in a higher temperature
atmosphere. The resistance/temperature coefficient of copper wire is about 0.4% for 1°C, and the coil
resistance increases with this ratio. On the other hand, coil resistance and the drop-out voltage will
decrease at lower temperature. Coil resistance change decreases with the same ratio at higher
temperature, about 0.4% for 1°C.
Therefore, please confirm the relay operation in every operating temperature range, with attention to
such temperature characteristic.
2. Ambient
temperature
characteristic
The ambient usage temperature should be set as around the relay inside the box because a heat
generated by a relay itself or other instruments causes increase of temperature inside the box.
5. Coil
impressed
voltage
3. Applied
voltage
Note that a coil impression with a voltage greater than or equal to the maximum continuous impressed
voltage may cause temperature rise which could cause coil burning or layer short. Furthermore, do not
exceed the usable ambient temperature range listed in the catalog. Please contact us regarding PWM
control.
