Power Supplies

Power Supply Glossary

Note. As a general rule, the ambient temperature is measured at 50 mm below from the Power Supply.

input voltage

The input voltage specifies the input voltage and corresponding frequency range at which the rated operations and performance can be maintained. The AC input oltages shown are effective values. An input voltage of 100 VAC is input when the input voltage selector terminals are shorted with a short bar and an input voltage of 200 VAC is input when these terminals are open.

Main applicable models: S82K (90 W, 100 W),S82J (300 W, 600 W)

Note. Models equipped with 100/200 VAC selection are delivered set to 200- VAC input. Therefore, be sure to thoroughly check the input voltage selector terminals before use. Using the incorrect voltage, whether 200 VAC or 100 VAC, will cause the Power Supply to malfunction.

100 V

200 V

Input Current

Standard Switch-mode Power Supplies directly rectify AC input current. Usually, rectification is achieved using capacitor inputs and a smoothing capacitor through which a reactive current is allowed to flow. Therefore, the input current depends on the output power, input voltage, power factor, and efficiency, as follows:

The power factor of a Switch-mode Power Supply is usually between 0.4 and 0.6. For details on efficiency, refer to the information in the datasheet for each model.

Input Rectifier/Smoothing Circuit

Internal Fuse

If the internal fuse has blown, it is very likely that internal circuits of the Power Supply have been damaged and that parts other than the fuse will also need to be replaced. If the fuse has blown,consult your OMRON representative.

Short-circuit current will not continue to flow on the primary side (i.e., the external side) of the Power Supply even if the fuse has blown. There is, however, no protection function for the input power lines.

Inrush Current

When a Switch-mode Power Supply is turned on, a surge of current flows into the input smoothing capacitor to charge the capacitor. This current surge is called the "inrush current." The inrush current varies depending on the application timing and the presence of an inrush current protection circuit, but is usually several to everal tens of times greater than the steady-state input current.

When two or more Switch-mode Power Supplies are connected to the same input, the inrush current is the sum of the inrush currents for each Power Supply. Therefore, check the fusing characteristics of fuses and operating characteristics of breakers making sure that the external fuses will not burn out and the circuit breakers will not be activated by the inrush current. The inrush current pulse width can be considered to be about 5 ms.
(Refer to the following diagram.) In particular, models with 100-to-240 VAC input have higher inrush current energy than models with single rated inputs or models with switching inputs. Therefore, consider the coordination with the breaker. The following table provides guidelines for fuse and breaker
selection.

Note. The duration of the inrush current is 5 ms max. Therefore, the fusing characteristics require the inrush current to flow sufficiently for up to 5 ms.

Leakage Current

Switch-mode Power Supplies have an internal noise filter circuit that prevents switching noise from being fed back to the input lines and protects the internal circuit from external noise.
Leakage current is largely due to the current that flows through the capacitors (C₁ or C₂) of the input filter circuit.
Depending on the Power Supply's configuration, leakage current can be reduced by incorporating an internal filter circuit.

Model with ACG Terminals

The ACG terminal on the S82W Power Supply, which is connected between capacitors C₁ and C₂ of the filter circuit, is short-circuited to the protective earting terminal by the short bar. Leakage current can be reduced by removing the short bar.
When the leakage current poses a problem, such as when using more than one Power Supply, remove the short bar from each Power Supply.

To prevent electric shock, however, be sure to ground the protective earting terminal.

In this case, however, the input filter cannot function effectively, resulting in greater output ripple noise and feedback noise.
To suppress this noise, connect an external noise filter circuit as shown below.

Leakage current cannot be reduced in Power Supplies without an ACG terminal due to the filter circuit configuration.
Model without ACG Terminals

ripple and Noise

Since Switch-mode Power Supplies operate at high frequencies (i.e., as high as 20 kHz or more), the DC output will contain ripple and noise. The following figure shows a representative waveform for ripple and noise.

Since ripple and noise contain high-frequency components, the ground line of the oscilloscope must be shortened when making measurements. If the ground line is too long, it acts as an antenna which is influenced by radian waves and, consequently, the correct values of ripple and noise cannot be measured.

voltage adjustment range

The range over which the output voltage can be adjusted while maintaining specific output characteristics.

Note 1.
The output voltage can effectively be converted to a value above the specified range. When adjusting the voltage, however, check the actual output voltage and make sure it is within the specified output voltage range.
Note 2.
Make sure that the output voltage × output current does not exceed the rated output capacity and that the output current does not exceed the rated output current.
Note 3.
Do not apply unnecessarily strong force to the Output Voltage Adjuster (V.ADJ). Doing so may damage the V.ADJ.

input variation influence

The variation in the output voltage occurring when only the input voltage is changed slowly over the input range while maintaining constant output conditions.

load variation influence

The variation in the output voltage occurring when the output current is changed slowly over a specified range while maintaining constant input conditions.

temperature variation influence

The variation in the output voltage occurring when only the ambient operating temperature is changed.

Dielectric Strength

When a high voltage is applied between the input terminals and the case (PE terminal), electric energy builds up across the inductor L and capacitor C of the internal noise filter. This energy may generate a voltage surge when a high voltage is applied to the Power Supply by a switch or timer, and as a result, the internal components of the Power Supply may be damaged. To prevent voltage impulses when testing, gradually change the applied voltage using the variable resistor on the dielectric strength testing equipment, or apply the voltage so that it crosses the zero point when it rises or falls. Some models of OMRON Switch-mode Power Supplies have surge absorbers between the input lines and between the input
terminals and the ACG terminal. When testing the dielectric strength of these models, emove the short bar from the PE and ACG terminals. With the short bar attached to the terminals, the applied voltage may be cut off by the testing equipment

(See following diagram.)

Insulation Resistance Test

To protect the Power Supply from an input voltage surge, surge absorbers are inserted between the input lines and between the input terminals and the ACG terminal. When testing the insulation resistance of the Power Supply, remove the short bar between the PE and ACG terminals on the front panel. Otherwise, the measured resistance will be lower than the actual value. (See following diagram.)

overload protection

Applicable Models: All Models

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.

Note 1.
Loads with built-in DC-DC converters (PLCs, 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.
Note 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.
Note 3.
If a load short-circuit occurs, the actual drop in voltage depends on the impedance of the load lines being used.
Note 4.
Even if the inclination of the drop characteristics is the same, the actual characteristics (output current/voltage, etc.) depend on the model.
Note 5.
Specific precautions apply to some models. For details, refer to the separate information in the datasheet for each model.

overvoltage protection

Main applicable models:
S82J (100 W/5 V, 24 V output,300 W, 600 W), S8TS,S8VM, S8VS, S8T-DCBU-02

This protection function detects overvoltage and interrupts output to prevent sensors or other loads from being subjected to excessive voltage due to failure of the Power Supply's internal recovery circuit. To resume operation, turn OFF the input power, and wait for a fixed period of time before turning ON the input power again.

Note 1.
When the overvoltage protection circuit operates, the Power Supply itself may be malfunctioning. When restarting the input power after the overvoltage protection circuit has operated, turn the input power ON with the load line disconnected and check the output voltage.
Note 2.
The overvoltage protection circuit may operate if surge or other external overvoltage (e.g., from the load) is applied to the output side.

Models with the Zener-diode clamp system do not restart after the protection circuit operates. Send the product for repair.

* For further details, refer to the datasheet for individual models

remote sensing function

Remote sensing can be used to compensate for a voltage drop on the load lines. (The compensation range is ±10% of the rated output voltage.)
To use remote sensing, remove the short bars from the remote sensing terminals (short-circuited in standard shipments) and wire as shown in the following diagram.
Make sure that the remote sensing screws are not loose. Loose screws will prevent output of the output voltage.
To ensure stable operation, it is advisable to thicken the load connection line and compensate for the amount of voltage drop using the Power Supply's voltage adjuster (V.ADJ).

Note 1.
When the voltage drop in the load lines is large, the overvoltage protection function may activate due to the increase in voltage to correct the voltage drop,so be sure to use as thick as a wire as possible.
Note 2.
Be sure that V_OUT × I_OUT does not exceed the rating of the Power Supply.

remote control function

The output voltage of the Power Supply can be turned ON and OFF from an external signal while the input voltage is being applied to the Power Supply. To use this function, remove the short bars from the remote control terminals (short-circuited in standard shipments) and connect the switch or transistor as shown in the following diagram. The output voltage will stop when the remote control terminals are open.
If the remote control screws become loose, output voltage may not be produced. Make sure that the screws are tight.

When a transistor is used, make sure that the collector-emitter voltage V_CE of the transistor is 20 V or higher and that the collector current IC is 5 mA or higher.

parallel operation

Connect Power Supplies in parallel to increase the output current if sufficient output current for the load cannot be obtained from one Power Supply.

List of Connection Methods and Main Models that Support Parallel Operation of Outputs

・ Up to two of the same model can be connected in parallel for the S82K (100 W) or S8VM (300 W, 600 W, 1,500 W), up to four of the same model can be connected in parallel for the S8TS and S8T-DCBU-02, and up to five of the same model can be connected for the S82J (300, 600 W).

・ The above table lists the main models for which parallel connection is possible. Refer to the datasheet for each model for details.
Attempting parallel connection for models that do not support it may result in an unbalanced load current, possibly causing the rated output current to be exceeded, so the parallel connection is not possible.

・ Use the same length and thickness of load connection line to ensure that the voltage drop between each Power Supply and load is the same.

N+1 Redundant Operation

Applicable Models: S8TS

Redundant operation is used in parallel connections of N Power Supplies (single operation when N = 1) of the same model,
where a redundant Power Supply is added to the number of Power Supplies (N) in parallel operation (N+1), thereby improving the reliability of the system.

series operation

Connect the Power Supplies in series to increase the output voltage.

List of Main Models that Support Series Connection of Outputs

・ The above table lists the main models for which series connection is possible. Refer to the datasheet for each model for details.
If models that do not support series connection are used, one of the Power Supplies may not operate when the AC Power Supply is turned on, possibly damaging internal circuits over a period of time.

・ If models with different power ratings or rated voltages are wired in series, keep the current flowing to the load below the rated output current for the Power Supply with the lowest power rating.

・ If the load is short-circuited when using an S82J-05024[][],S82J-10024[][], S8VM-15W/30W, S8VS, or S8TS-02505[],reverse voltage will occur inside the Power Supply, which may cause Power Supply deterioration or damage. It is recommended to connect the diodes (D1 and D2) as shown in the above diagram.
Guidelines for the type, dielectric strength, and forward current of the diodes are as follows:

・ Type:
・ Schottky barrier diodes.
・ Dielectric strength (V_RRM):
Twice the rated output voltage of the Power Supply or higher.
・ Forward current (I_F):
Twice the rated output current of the Power Supply or higher.

backup operation

Two Power Supplies can be wired in parallel even though each has a sufficient power rating. This can be done to ensure (back up) Power Supply even if one of the Power Supplies fails.(Backup operation is possible for all Power Supplies with single outputs.)

Use the same model of Power Supply for A and B.

・ Select the Power Supplies A and B so that either has a sufficient power rating for the load.

・ Be sure to connect diodes to both Power Supplies A and B, as shown in the diagram, so that the Power Supply backing up the faulty Power Supply is not affected.

Guidelines for the type, dielectric strength, and forward current of the diodes are as follows:

・ Type: Schottky barrier diodes.
・ Dielectric strength (V_RRM):
The rated output voltage of the Power Supply or higher.
・ Forward current (I_F):
Twice the rated output current of the Power Supply or higher.

・ Increase the output voltage settings of Power Supplies A and B just enough to allow for the voltage drop (V_F) on diodes D₁ and D₂.
Also, make sure that the diodes are sufficiently cooled so that their temperatures remain below the catalog value.
This is necessary to control the power loss (output current of Power Supply I_OUT × diode forward voltage V_F) resulting across the diodes.

・ Some power loss to the load will occur due to the load power and diodes. Therefore, do not exceed the rated power (rated output voltage × rated output current) of the Power Supply.

Creating ± (Positive/Negative) Outputs

・ The floating output (the primary and secondary circuits are separated) enables creating ±outputs using two Power Supplies. To create± outputs, connect two of the same model of Power Supply as shown in the diagram.

・ All models of Power Supply can be used to create ± outputs. If there is the possibility that another load is wired in series, such as a Servomotor or operation amplifier, as shown in the diagram, connect bypass diodes D₁ and D₂ as shown in the diagram. Without these diodes, the Power Supplies may not start when power is turned ON, possibly damaging internal circuits over a period of time.

No diodes are required for models that support series operation.

・ Guidelines for the type, dielectric strength, and forward current of the diodes are as follows:

・ Type:Schottky barrier diodes.
・ Dielectric strength (V_RRM):
Twice the rated output voltage of the Power Supply or higher.
・ Forward current (I_F):
Twice the rated output current of the Power Supply or higher.

Harmonic Current Suppression

What is Harmonic Current?

Most switch-mode power supplies incorporate capacitors. As a result, the input voltage sine wave is transformed into steep input current pulses.

If this current is provided to the power-receiving equipment of factories or buildings, the equipment will generate excessive heat that may damage the equipment itself, while also consuming unnecessary energy. This has become a public problem as well.

Harmonic Current Control

As an international standard, IEC555-2 was enacted for the limitation of harmonic current emission. IEC1000-3-2, as a revised standard replacing IEC555-2, was established in 1994.
In conformance with the IEC1000-3-2, EN61000-3-2 was established and will come into effect in European countries in January 2001 Power Supplies with a capacity of 75 W or higher.
In Japan, the Ministry of International Trade and Industry provided some guidelines for the suppression of harmonics generated from electrical household appliances and electrical equipment. Japanese manufacturers have been voluntarily issuing and abiding by the guidelines.

Main Applicable Models

S82K-P[][][]24 (200-V Series only)
S8TS
S8VS
S8VM (50, 100, 150, 300, 600, 1,500 W)

Note. Buzzing Noise when Turning ON Input A noise may occur when turning ON the input of models incorporating harmonic current suppression circuits. This is a transient noise that occurs only until the internal voltage has stabilized and does not indicate any problem in the product.

・ Main Applicable Models:
S8TS
S8VS (120, 180, 240 W)
S8VM (50, 100, 150, 300, 600, 1,500 W)

life expectancy

The life of a Power Supply is determined by conducting a temperature rise test of the built-in aluminum electrolytical capacitors, when using the Power Supply in a standard installation at the rated input voltage under an ambient temperature of 40°C and a load rate of 50%. The calculated life expectancy functions as a guide only is not a guaranteed value.
Use this information as reference for performing maintenance and replacement.

Note. The life expectancy of the fan in models with fans is not included.

(Main Models)

Eight years or longer:S82K
Ten years or longer:S82J, S8TS, S8VS, S8VM

Reference Material for Power Supplies

Typical Safety Standards for Noise

Values Stipulated for Conducted Emissions in Various Countries

CISPR:
Applied to office equipment.
FCC:
Noise regulation in U.S.A.
Class A:
industrial equipment
Class B:
household appliance and information equipment including communications equipment.
VDE:
Noise regulation in Europe
(European version of the FCC used in U.S.A)

Japan Electric components regulations:regulations applied to household and industrial electric equipment in Japan

VCCI:
Applied to data processing devices in Japan.

Selection of Wires

Wires for the Power Supply should must be carefully selected. Refer to this table when selecting the wires.

Recommended Maximum Current:
The table is applicable to wires with 1 to 4 conductors. Keep the Current value to within 80% of the values shown in this table when
using wires having 5 or more conductors. The following chart shows the voltage drop per meter in terms of the relationship between
the Current and conductor diameter. Make sure that the Current value does not exceed the recommended maximum Current value.

Voltage Drop per Meter

(UL1015 Vinyl-sheathed Wires for Heat-resistant Equipment)

Note.
The current indicates the allowable current. In practice, application must be below the recommended current values.

Maintenance

There are slits in the Power Supply to allow heat generated inside the Power Supply to escape. Dust or other foreign matter can enter through these slits and cause the output to be reduced or stopped. Perform periodic maintenance and vacuum out an dust or other foreign matter.