When a failure occurs in the application and heat of the electric wire is generated due to the overcurrent of the load, is there a way to limit the overcurrent to prevent abnormal heat generation of the wire?

By the auto shift function, overcurrent protection(OCP) point level is changed to suppresses the output current. As a result, heat generation is prevented.

Auto shift of overcurrent protection (OCP) point level.

The power supply has an OCP function which limits the output current to not flow beyond a certain value. The current value at which the OCP function operates is set higher than the rated current of the power supply. If there is a large current flow due to an abnormal load, the power supply will limit the output current by the protection function.

For loads such as fans in which a larger current flows during the startup than steady operation, a power supply with enough capacity should be selected.

When an abnormality occurs inside the application and an excessive current (abnormal current) flows, the output current is limited by the overcurrent protection function, but the abnormal current continues to flow from the power supply (Fig.1).
In some situations, the abnormal current might continue to flow less than the OCP point but more than the rated current. (Fig. 2).

If the thickness of the wire is selected based on the continuous current, the wire might not have enough current rating for the overcurrent level when an abnormal issue happens. This could cause burning due to the heat in the wire. Secondary damage could also occur.

Fig.1 　Abnormal condition 1

Fig.2 　Abnormal condition 2

The concept of OCP auto shift function is to switch the OCP point automatically to the programed setting by detecting the operating time. This function enables to achieve both peak current capability at start-up and current limit for an abnormal condition by switching the OCP operating point during start-up and steady state operation.

Fig.3 　Auto shift of overcurrent protection (OCP) point level

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Application example

• Belt conveyor
• Motor driver
• FAN etc.

Other examles

Examples of power supplies that can be modified

• PCA600F

With modifications, various functions can be added.