Industrial power supplies with up to 350% peak load capability

Many applications, especially in the electromechanical field, require high peak current for brief periods of time. Generally, this applies to motors for pumps or drives, which often require significantly more initial power to overcome mechanical resistance during the start-up process. It may also be that sub-areas of an application are switched on briefly and repeatedly, depending on requirements, also causing brief intervals of higher power consumption. At the same time, the average power requirement remains considerably lower than the peak demand. It is therefore important to choose a power supply unit than can supply the average power but which can still supply the temporary peak load. A power supply dimensioned to the average power but which also offers peak load capability offers no disadvantages in expected operational lifetime or likelihood of malfunction compared to a larger unit dimensioned to the peak load.

How power supplies behave when overloaded
Generally speaking, power supplies offer a range of protective functions. If current draw is too great – i.e. if a power supply unit is overloaded – the overcurrent or overload protection circuit responds within a defined range. The overload protection circuit can be designed in various ways. Two examples:

• In the event of an overload, the power supply reverts to what is known as constant current limiting: when the protection circuit responds, the output current is limited to a fixed value and is output constantly, while at the same time the voltage at the power supply is reduced towards zero.

• The power supply goes into hiccup mode: If excessive current or excessive power draw is detected, the power supply shuts down. After a defined period, it restarts, then switches off again if the fault condition persists. This continues until the fault has been rectified.

Hiccup mode is not suitable for motor applications where the power supply, as a result of the high starting currents associated with the motor start-up process, can move into the overload range. A power supply unit that reacts to an overload with constant current limiting could, depending on the design, still get the motor to start slowly in case of an overload. However, the voltage drop means that any additionally connected electronics can no longer be supplied with power. For applications where a nominal speed has to be reached quickly and dynamic motor processes are called for, it isn’t enough to simply push the power supply unit to its limit.

► It would be possible in this situation to use a power supply that offers correspondingly higher output, but this would result both in a higher case volume and a significantly higher purchase price.

''Peak Power''→ Power supplies with peak load functionality
Power supplies in the HRP-N3 series, like MEAN WELL's HRP-300N3-12 pictured above, can deliver up to max. 350% peak power, based on the rated power of the unit. It is important to determine whether the required peak power demand of the specific application can actually be supplied.
Peak power is provided for a maximum of five seconds per cycle.
The average of peak and non-peak power drawn from the power supply unit cannot exceed its rated power, and the time ratio of peak power to non-peak power should not exceed 35 percent. With these parameters in mind, the HRP-300N3-12, with nominal power of 324W, can provide of up to 1050W of peak power.

Efficient power supply as an important criterion for operational maintenance of the power supply and the entire end application
If a power supply unit is significantly overdimensioned and therefore only operated at partial load for a long period of time, the average efficiency is normally not very high. The power loss, dissipated as heating of the internally installed passive and active components, thus leads to unnecessarily excessive heating. The heating of a power supply directly affects its expected operational lifetime, and operating temperatures should therefore be kept as low as possible.

HRP-N3 series power supplies with 150W to 600W rated power and 450W to 2100W peak power (at 5% duty cycle) are suitable for installation in environments with operating temperatures from -40 to +70℃. With their high power density, peak power, and efficiency, they offer savings on both physical space and money. Additional functions such as a DC OK signal, remote sense, and adjustable output voltage increase application flexibility. MEAN WELL offers a 5 year guarantee on its HRP-150N3, HRP-300N3 and HRP-600N3 power supplies.

Schukat electronic sells power supplies from a range of manufacturers, including MEAN WELL, Self Electronics, and Recom Power. Schukat stocks around 6000 different types of power supplies and DC/DC converters in production quantities at its automated central warehouse in Monheim am Rhein, Germany.

As a distributor, we provide fast, competent support with direct contact persons in-house, and also have an expert field service team for on-site problem solving. Customers benefit from rapid processing of inquiries, availability of data sheets and samples, and variable delivery quantities – from samples to series production.

Our technical sales team is here to help when selecting suitable power supply products as well as for any customer-specific questions relating to peak power.