Backup power supply for Unipi units (DRC-60B)

The following tutorial describes how to connect Unipi units with the Mean Well DRC-60B power supply, which allows the output power to be backed up using batteries. It is also necessary to stabilize the power supply's output voltage using a DC/DC converter.

This power supply is used to supply power, but also to charge and maintain charged batteries. It can be operated, subject to the conditions described below, with all Unipi units and other selected Unipi equipment. In the event of a mains power failure, the power supply switches seamlessly to battery power mode. This achieves an uninterruptible power supply.

Unipi 1.1

Elements used

  • Wires of different colours (Cu, 0.5mm2)
  • Switched power supply Mean Well DRC-60B with UPS function
  • DC/DC converter Mean Well DDR-15G-24
  • Any 12 V⎓ acid-lead batteries (e.g. 2× CSB HR1234W 12V/9Ah)
  • Unipi Patron S207 unit

The DRC-60B power supply can be supplied with an input voltage of 110 / 230 V~. The power supply's output can achieve a maximum voltage of 27.6 V⎓ with a maximum current of 2.15 A. In combination with a suitable voltage regulator (DC/DC converter), it is ideal for powering all Unipi units from the Patron, Neuron, Axon, and Unipi 1.1 product lines. The DRC-60B itself, without the converter, can be used to power Unipi Gate product line devices, as it can be powered with voltages in the 9–30 V⎓ range. For S-size units, the DDR-15G-24 converter can be used. For M and L sizes, the DDR-30G-24 should be used. Unipi 1.1 needs to be powered with 5 V⎓, so a suitable choice is e.g. DDR-15G-5.

The power supply powers the connected load (Unipi unit) and simultaneously charges and maintains the batteries. The total output current of the power supply is up to 2.15 A, of which 0.75 A is reserved for charging the batteries and 1.4 A for the load at the output.

The DRC-60B power supply is also equipped with two signal relay outputs:

  • AC OK is switched on when the corresponding voltage is connected to the input of the power supply
  • Bat. Low is switched on if the battery voltage falls below 22 V⎓

Switched on Bat. Low indicates that the battery is almost discharged. The remaining time depends on the state of the batteries and the connected load. This state is used to save the current values, set the safe state of the outputs, and other necessary tasks, e.g. sending a warning SMS message.

Wiring diagram

Fig.1 - Wiring diagram of DRC-60B, DDR-15G-24, 2x CSB HR1234W and Unipi Patron S207

Wiring description

  • First, connect the output voltage (+V, -V) of the DRC-60B power supply to the input terminals of the DDR-15G-24 converter (+Vin [4], -Vin [3]).
  • The output voltage from the converter (+Vo [1], -Vo [2]) is connected to the power supply terminals of the unit.
  • The conductor from the converter terminal -Vo [2] is connected to the DIGND terminal of the digital inputs of the unit.
  • The conductor from the converter terminal +Vo [1] is connected to the first terminal of the Bat.Low signal relay and the first terminal of the AC OK relay.
  • The second contact of the Bat.Low signal relay is connected to digital input DI1 and the second contact of the AC OK relay is connected to DI2.
  • Before connecting the batteries, the maximum output voltage of the power supply must first be set using the +V ADJ trimmer. The voltage must match the holding voltage of the batteries, in the case of our wiring the voltage is set to 27.4 V⎓ to achieve a voltage of 13.7 V⎓ on each of the batteries.
  • The batteries must be connected in series: the positive terminal of battery 1 is connected to the negative terminal of battery 2.
  • The negative terminal of battery 1 is then connected to the -Bat. power supply terminal. The positive terminal of battery 2 is connected to the +Bat..
  • Finally, connect the conductors (, N, L) to the respective terminals of the power supply.
  • Before the input voltage is connected for the first time, the power supply output is disconnected even when the batteries are connected and fully charged. Therefore, the input voltage must also be connected for full operation. When the input voltage is subsequently disconnected, e.g. power outage, the power supply output then switches seamlessly to battery power mode.
  • When selecting the power supply protection, a current surge (inrush current) of up to 60 A must be taken into account when switching the input of the power supply.
  • Neither the power supply nor the converter requires additional cooling.
  • The input of the power supply should be preferably treated with a suitable surge arrester.
  • The DRC-60B power supply meets the requirements for safety transformers and is a small safe voltage (SELV) power supply.

  • Unipi Patron S207 with the backup of 2pcs of 12 V⎓ / 9 Ah batteries can run on these batteries with occasional relay switching up to 72 hours.
  • Unipi Patron S167 LTE when backed up on the same setup will run on batteries (with good signal and minimal LTE usage) for up to 54 hours.



Fig.2 - Dimensions of DRC-60B

Fig.3 - Dimensions DDR-15G-24