By Mr. Kai Li, Project Manager of MEAN WELL
RS “Ask the Expert” series draws on the expertise and long experience of key industry subject matter experts (SMEs) in the more than 550 worldwide suppliers we work closely with to solve our customer’s problems – big and small.
Many of our customers are faced with the issue of selecting DIN rail-mounted power supplies for their equipment in domestic, commercial and industrial environments. The selection of power supplies involves more than the power supply unit itself, but also the accessories that support its safe, reliable, flexible, and economical operation.
Focusing on the standard SPS market, MEAN WELL carries over 10,000 models of standard power supply products and accessories to provide power solutions for all types of applications. This article will discuss the components required to create DIN Rail-Mounted Automation Power Solutions with Mr. Kai Li, Project Manager of MEAN WELL.
What are the primary parameters for the selection of a DIN rail-mounted power supply?
As with all power supplies, the application dictates the parameters of the power supply. The wattage of the load to be supplied dictates the current capability for the AC service feeding the AC-DC power supply. MEAN WELL’s power supplies can accommodate the common AC sources such as 120V, 240V and 480V and provide a range of DC output voltages, including 5V, 12V, 24V and 48V. These power supplies are convection cooled and do not require a fan that decreases efficiency and draws dust into the power supplies. They can operate successfully over an ambient temperature range of -20°C to +70°C. Currently, MEAN WELL’s maximum DIN rail-mounted power supply is the 960W (WDR/TDR-960).
Wattage: 240W~960W
Features:
- Metal case, slim size
- 3∅, 340~550VAC input
- High efficiency up to 94.5%
- Built-in active PFC function
- Assemble on industrial rail TS-35 / 7.5 or 15
- Built-in DC OK relay contact
The MEAN WELL DIN rail-mounted power supplies are used in many sensitive circuits that cannot tolerate power interruptions. How do they handle this issue?
MEAN WELL’s DBUF20/40 series of DIN rail-mounted 20A/40A buffer modules can be used to provide short-term backup for the load when the AC source power is temporarily interrupted. At 24V DC, the DBUF20 can sustain a 20A load for 350ms, and the DBUF40 can sustain a 40A load for 250ms. There is no external battery in the system, which reduces maintenance costs – eliminating periodic battery testing and replacement.
MEAN WELL also makes the DIN rail-mounted battery-based DR-UPS40 uninterrupted power backup function. The backup time can be longer, but the battery needs to be replaced regularly, increasing maintenance costs.
But what if the AC power interruption is longer than about 1 minute?
In that case, it would be best to use an Uninterruptable Power Supply (UPS) such as the MEAN WELL DR-UPS40. It is a 40A max DC UPS for a 24VDC power system. It can carry a load of 40A for a period of time, depending on the battery size. So, the system designer must determine the time desired and what battery capacity would be required to maintain the load for that time. Usually, the time required allows the operator to shut the system down in an orderly fashion or manually switch to an alternate AC source. The unit provides system monitoring signals (LED lights) to indicate DC BUS OK, Battery Fail, Battery Discharge, and the repeated Battery Test function to check the condition of external batteries.
In some industrial applications, any Power Supply Loss cannot be tolerated. Does MEAN WELL have a solution to that problem?
A MEAN WELL redundancy module can be mounted on the same DIN rail as the power supply to solve this problem. Upon loss of the preferred power supply, the redundancy instantly disconnects the faulty power supply and connects an identical unit to replace it.
What type of cooling system does MEAN WELL use to ensure that its DIN rail-mounted can operate properly in the stated temperature range of -20°C to +70°C?
MEAN WELL recognizes that heat is the enemy of all electric equipment. Therefore, instead of relying on fans that can fail, MEAN WELL designs its DIN rail-mounted equipment to be adequately cooled by natural convection within the enclosure.
How Does MEAN WELL assure the quality of all of its DIN rail-mounted power supplies?
MEAN WELL views quality manufacturing and product processing as a priority. Since 1994, MEAN WELL has held the ISO9001 certification and implemented an audited total quality management (TQM) system. In addition, MEAN WELL has held the ISO14000 certification since 2013 and obtained the OHSAS18001 system in 2015 to implement environmental protection actions to create a safe and healthy life for customers and employees alike.
MEAN WELL DIN Rail power supply products comply with UL / CUL / TUV / CB / CE / GL / SEMI certificates, including UL508, UL61010, UL1310, UL60950-1, UL6238-1, TUV EN60950-1, TUV EN62368-1, TUV EN61558-1/-2-16, IEC 60950-1, SEMI F47, GL, EN55011, and EN55022.
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