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FAQ01913 of Power Supplies FAQ

FAQ No. FAQ01913

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Question

What is overload protection function?

Answer



This protection function prevents damage to the Power Supply itself due to overcurrent (including output short-circuits). The protection function is activated and the output current is limited when the load current is greater than the overcurrent detection value (this value depends on the model).

The output voltage will also drop according to the overload (load impedance).

The drop level depends on the overload conditions and load line impedance.

The following table shows the six types of output voltage drop characteristics for main models when the overcurrent protection function is operating.

These drop characteristics can be seen as indicating the limit on the output current that can be supplied to the load effectively in the process in which the output voltage starts when the AC input turns ON. When connecting a load (with built-in DC-DC converter) that starts operating from a low voltage or a capacitive load in which inrush current can flow easily, consider the trend in overcurrent protection drop characteristics and the startup characteristics on the load side when selecting the Power Supply.

Generally, an inverted L voltage drop is considered favorable at startup.

Overcurrent
drop
characteristics
Relationship
between
output voltage and
output current
TrendMain models
Gradual
current/
voltage drop
When a voltage drop occurs, the output
current also gradually drops, and the
output returns to the normal level
automatically (automatic recovery)
when the overcurrent status is cleared.
S82K: 3 W, 7.5 W, 15 W
S8VS: 15 W
Inverted L
voltage drop
When a voltage drop occurs, the output
current remains essentially constant.
The output returns to the normal level
automatically (automatic recovery)
when the overcurrent status is cleared.
S82J: 100 W (5 V, 12 V, 15 V),
150 W, 300 W
S82K: 90 W, 100 W
S8TS
S8T-DCBU-02
S8VS: 240 W
S8VM (12, 15, 24 V):
50 W, 100 W, 150 W, 300 W,
600 W, 1,500 W
Voltage/
current drop
Intermittent
operation
When a voltage drop occurs, the output
current also gradually drops, and the
load of the Power Supply itself is
reduced (automatic recovery) using
intermittent output when the voltage
drops to a certain level or lower.
S82J: 10 W, 25 W
Inverted L
voltage drop
Intermittent
operation
When a voltage drop occurs, the output
current remains essentially constant.
The load of the Power Supply itself is
reduced (automatic recovery) using
intermittent output when the voltage
drops to a certain level or lower.
S8VS: 30 W, 60 W, 90 W,
120 W, 180 W
S8VM (5 V): 50 W, 100 W,
150 W, 300 W, 600 W
Gradual
current
increase/
voltage drop
Intermittent
operation
When a voltage drop occurs, the output
current increases as the voltage drops,
maintaining constant power, and the
load of the Power Supply itself is
reduced (automatic recovery) using
intermittent output when the voltage
drops to a certain level or lower.
S82J: 50 W, 100 W (24 V)
S82K: 30 W, 50 W
S8VM: 15 W, 30 W
Inverted L
voltage drop
Shut off
When a voltage drop occurs, the output
current remains essentially constant. If,
however, the overcurrent status
continues for longer than a fixed time,
the output will be interrupted and the
power will need to be turned ON again
to recover.
S82J: 600W

Note:

1.Loads with built-in DC-DC converters (Programmable Controllers, digital panel meters and other electronic devices) and capacitive loads are connected, the overcurrent protection function will be activated at startup, which may prevent the Power Supply's output from turning ON.

2.Continuing to use the Power Supply with an output short-circuit or in overcurrent status may cause the internal parts to be deteriorated or damaged.

3.If a load short-circuit occurs, the actual drop in voltage depends on the impedance of the load lines being used.

4.Even if the inclination of the drop characteristics is the same, the actual characteristics (output current/voltage, etc.) depend on the model.

5.Specific precautions apply to some models. For details, refer to the separate information in the datasheet for each model.

Applicable Models: All Models

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