ELCA Current Rectifiers for Electrolysis

  1. Applicable standards
  2. Control
  3. Low voltage Transformers
  4. Semiconductors
  5. Protections and alarms
  6. Fuses
  7. DC current measuring system
  8. Cabinet
  9. Painting
  10. Ambient conditions / Installation
  11. Protection degree
  12. Noise level
  13. Busbars/ power connections
  14. Documentation
  15. Testing

Applicable standards
CEI EN 60146 (IEC 146), Rectifier unit
CEI EN 61558, low voltage transformer
IEC 76 / IEC 726, medium voltage transformer
CE Marking, in conformity with Low Voltage directive 2006/95/CE and with directive 2004/108/CE (electro-magnetic compatibility directive EMC)

Control
Electronic control by means of SCRs, on primary or secondary side of the power transformer, with Constant current stabilization, 0 ÷ 100%, by thyristor. The set value, adjustable by means of a 10 turn potentiometer (or by using an external signal) is compared with the current feedback. The output voltage is changed accordingly, in order to keep the preset output current constant.
Accuracy: ±1% of rated value for load variations from 10 to 100%.
Soft start: ramp time (2 ÷ 20 Sec.) adjustable by means of trimmer on control card.

Low voltage Transformers
Dry type, air cooled, Max. temperature rise 100°C (40°C ambient).
Insulation: class H.
Primary windings: electrolytic grade copper or electrolytic grade aluminum (99,5%).
Secondary windings: electrolytic grade aluminum (99,5%).
The transformer is tagged with the serial number , the date of manufacture and all relevant parameters.

Semiconductors
Module or stud or hockey puck type SCRs with blocking voltage of minimum 3 times the applied voltage. Single or double side cooled by means of finned aluminium heat sinks (air cooling) or by means of demi water (water cooling).
Max. working junction temperature kept at least 15°C less than the max. allowable device junction temperature at rated current and at the max. temperature of the cooling media.

Protections and alarms
Automatic main breaker against overload on ac side (low voltage supply).
RC snubber circuits parallel connected to supply line and to SCRs against surge voltage.
Extra fast fuses against internal short circuits and SCR fault.
DC output current limiting device against overload (dc side) and SCR firing pulse suppression device (fast overload).
Max temperature thermostats placed on SCR heat sinks and in the main transformer windings against over temperature.
Auxiliary circuits protected by fuses or automatic circuit breakers.
Wrong phase sequence device.

Fuses
Extra fast fuses, whit trip indicator, series connected to each SCR (output d.c. current higher than 500 Adc).

DC current measuring system
Shunt 60 mV - class 0,5 – DIN 43703.

Cabinet
Cabinet, frames and panels: painted carbon steel.
Hardware (bolts, nuts, screws): galvanised carbon steel (stainless steel on request). Door to access control section.
Gasketed removable panels are provided for inspection and service.

Painting
Epoxy powder, Elca standard painting. Min. thickness : 80 micron.
Standard RAL 7032. Different RAL colours on request.

Ambient conditions / Installation
Indoor installation, ambient conditions according to IEC146 -1-1; to be specified if different.

Protection degree
Air cooling: Protection degree is IP 20. Ventilation openings are fitted with 12,5 mm mesh screen. Different IP on request.
Water cooling: Protection degree is IP 54.

Noise level
Not higher than 85 db at 1 meter (indicative value).

Busbars/ power connections
Electrolytic grade copper and / or aluminium (99,5% - alloy 1050A).

Documentation
The standard documentation consists of:
Electrical schematic drawings showing all circuits, complete with wire numbers.
Mechanical cabinet outlines and dimensions; Control panel layout; Control device location, terminal block(s).
Bill of materials.
Instruction manual.
Test reports.

Testing
According to Elca test procedure and CEI EN 60146 (IEC 146).