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Application specific requirements
Weidmüller – power supply solutions for all applications
Increasing the output power
Individually adapting the output power by directly connecting power supply units in parallel.
- INSTAPOWER power supply units: up to 3 devices can be connected in parallel
- PRO-M power supply units: up to 5 devices can be connected in parallel
- Indication of the failure of individual devices can be achieved using optional diode modules
To ensure the most even distribution of the load within the parallel connected power supply units, the voltage difference must not be more than ± 50 mV. This balance is achieved when the plus wire is connected. Symmetrical wiring also helps to distribute the current uniformly.
Galvanic isolation and stabilisation
DC/DC converters galvanically isolate the input from the output voltage and prepare them:
- to compensate for voltage losses which occur due to the higher cable resistance
- to avoid ground loops which can occur in plants which are spread over a large area
- A potential-free alarm relay and a transistor output give you full status monitoring
- Special versions, supplied as protection class III devices, mean that you can use them in floating earth systems such as might be found when operating back-up batteries
Uninterruptible power supply
Mains interruptions and brown-outs are a frequent cause of system failures. Battery-supported or capacitor based uninterruptible power supply units (UPS) units cover these types of mains network faults and thereby increase system availability.
- Different status relays permit status monitoring
- The UPS control unit monitors the input voltage and, in the event of a fault, switches immediately to battery operation
- When the power is restored, the input voltage is again switched over to the load and the battery is recharged
- An integrated deep-discharge protection system and an optimised charge curve ensure that the battery has a long service life
Power reserve for peak currents
For selective triggering of circuit breakers or for short-term additional power reserves, a capacitor module can be integrated into the 24 V circuit.
- The integrated alarm relay monitors the input voltage, thereby monitoring the status of the 24 V DC power supply
- Sufficient power for the pulse triggering of circuit breakers (MCBs)
- To further increase the power reserves, multiple capacitor modules can be connected in parallel
The capacitor module can be used independently of the output power from the power supply modules. When triggering circuit breakers, the line impedance must be observed (see main catalogue, 4.3).
Redundant power supply units
The availability of the power supply units is increased by the use of redundant circuits. Here, each individual power supply unit can cope with the total load required in the event of a failure by itself.
- Separate voltage monitoring of the input channels (alarm relay)
- Full status monitoring including voltage monitoring of both inputs thanks to the integrated Alarm relay
- Diode modules give you 100 percent redundancy – this is also known as “true redundancy”
An example of redundant power supply units
- for an output current of 20 A: 2x PRO-M, 20 A + 1x CP M DM20
- for 40 A output load: 2x PRO-M, 40A + 1x CP M DM40
Selective load protection
The breakdown of the whole secondary load into individual load circuits which have quick-operating safety elements in case of a fault is known as selective load protection. Electronic fuses are ideal to meet the special requirements found in selective load protection.
- The tripping characteristic curve of the electronic fuse is, on the one hand, fast enough to switch off the faulty circuit quickly; and on the other, tolerant enough to deal with a motor start-up or capacitive loads
- A switch to turn the output on or off means that it is simpler to diagnose errors and to commission
- The fuse triggering is signalled via a potential-free alarm relay
Uniform distribution of a load current over two power supply units using active current sharing.
- A significant increase in the availability of the whole power supply results as each power supply unit only ever operates at a maximum of half the nominal current
Always use devices of the same type. Active current sharing is achieved using the redundancy modules CP T RM10 and CP T RM20.
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