Double input power unit
1000 VA, Hydro-Quebec

Part # 020-0055-00

The supply unit is made up of two DC to AC converters operating in redundant mode. It generates power capable of supplying a continuous load of 1000 VA.

A quick undervoltage sensing device at the output of both converters prevents operation below nominal voltage due to an overload or a short-circuit. This device acts on relays that enable load transfer from the first inverter to the second one within a delay not exceeding half a cycle. The supply line is used as a last resort. This unit is mounted in a shielded box that protects it against electromagnetic inteference. This box meets the requirements stated in standard CEI 297, i.e.:

  • Undervoltage : 120 Vac - 15% ± 5% max.
  • Transfer time : 16 ms max.
  • Surge protection : 18-sec delay upon reset
  • Disconnecting : 2 output fuses for each inverter
  • The power unit must be able to supply a 1000 VA load at all times when it is supplied by a 125 Vdc source.
  • The operation of the supply unit is as follows :
    • Malfunction of DC to AC inverter 1 : transfer of the load onto DC to AC inverter 2.
    • Malfunction of DC to AC inverter 2 : transfer of the load onto the 120 Vac supply line.
  • The switching of the sources is carried out through undervoltage sensors (27) at the unit output. The load transfer may result from internal defects in the inverter as well as external faults (loss of direct current and load).
  • Both redundant DC to AC inverters are part of a new generation of converters at the forefront of technology. Both units convert 125 Vdc into a 120 Vac sine wave; they can supply any electric equipment of 1000 VA or less.
  • The TRANSTRONIC inc. DC to AC inverter is designed to support external faults. Among the protection circuits they are current limit, short-circuits, overvoltage and undervoltage as well as input polarity reversal.
  • The supply unit is designed to meet or exceed the standards specified in the technical notice SN.62-1008d.


Nominal voltage : 125 Vdc

Current : 9.4 Acc @ 125 Vcc, à charge nominale

- Output cutoff for an input voltage outside the operating range (from 105 Vdc to 140 Vdc ± 2 Vdc);
- Reverse polarity protection;
- Fuse, filter choke and protection diode.


Nominal voltage : 120 Vac.

Power : 1000 VA (8.3 Arms at 120 Vac)

Overload current : 10 Arms ± 1 Arms, 10 sec minimum

Short-circuit current : 22 Arms ± 2 Arms, 2 sec.

Load regulation : ± 6 Vac between the no-load voltage and the full-load voltage.

Line regulation : ± 1 % of 105 Vdc at 140 Vdc.

Wave shape : Sine wave (THD < 2.8 % on load)

Frequency : 60 Hz ± 0.05%

Load type : cos ø 0.9 capacitive at cos ø inductive at 1000 VA.

- Output cutoff after a short-circuit lasting over 2 sec; automatic reset after 30 sec
- Thermal protection on output stage (95ºC).
- Galvanic isolated output


Performance : 85 % minimum at 1000 VA nominal load

Dimensions: Width : 483 mm (19") Height : 265.9 mm (10.5") Depth : 305 mm (12")

Weight : 41 kg (90 lb).

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