B50 series automatic capacitor banks

B50 series THDi ≤ 50%

Industrial plants where the load varies greatly throughout normal operation will require automatic P.F. equipment in order to connect the necessary capacitive power. 

More details

Technical characteristics

  • Rated voltage: 400Vac
  • Rated frequency: 50Hz (60Hz on request)
  • Voltage of auxiliary circuits: 110Vac
  • Working temperature range: -10°C/+50°C
  • Cubicle: 20/10mm sheet steel, protected against corrosion by a phosphating treatment. Epoxy powder painted, RAL 7035 color (other colors on request) External Protection Degree: IP30 (type S-M), IP40 (Type L) Locking system: by screw for cubicle type S and type M by key for cubicle type L
  • Ventilation: Forced
  • Isolating switch: Three-pole with door interlocking device
  • Supply: Type S: entry of the cable from the top/bottom Type M: entry of the cable from the top Type L: entry of the cable from the bottom
  • Wiring: By N07VK CEI 20-22 flame retardant cables. Auxiliary circuits are identified as in the electrical drawing
  • Contactors: Each bank of capacitors is controlled by a three-pole contactor. To limit the overcurrent peaks , each contactor is provided with insertion resistors. Rated voltage of auxiliary circuits: 110 Vac, 50 Hz.
  • Fuses: Each bank of capacitors is protected by a set of three fuses (NH00 type) with high breaking capacity. Also the auxiliary circuits are protected by fuses.
  • Capacitors B50 550 Vac Series Single phase of type self-healing, made up of metalized polypropylene, equipped with overpressure safety device and discharge resistor. Filling: biodegradable non toxic dry type, PCB free. Manufactured using new technologies of metallization. Delta connection. Capacitance tolerance: -5% +10% Dielectric losses: <0.3W/kvar Temperature class: -25°C (55°C)
  • Regulators: Varmetric measurement by means of a C.T. (Current Transformer)(secondary 5A) not supplied
  • Reference Standards: Comply with L.V. 73/23 (93/68) EEC Directive Capacitors: CEI EN 60831-1/2 Equipment: CEI EN 60439-1, CEI EN 61921-1
  • Options (on request): Automatic switch Isolator with fuses Protection degree : IP55 Type M: entry of the cable from bottom Type L: entry of the cable from the top

Power Factor Correction in presence of harmonics

In recent years, Power Factor Correction has evolved greatly due to the presence of generated harmonics by the loads. These loads produce harmonic currents and voltage which distorts the network waveforms. The main sources of harmonics are generated by AC/DC static converters and UPS systems. For these reasons it is essential that any installation of Power Factor Correction equipment must be carefully evaluated. The possible presence of harmonic currents in the network could create conditions of parallel resonance between the inductance of the network and the capacitors, generating overcurrents and overvoltages, which would cause premature failure of the power factor correction capacitors. The ideal power factor correction solution for any system must be determined by examination of the system parameters and harmonic spectrum.

Power factor correction

Level of current harmonic distortion allowed in the equipment

THDiC % on the capacitorsTHDIi % on the networkCapacitor banks
≤ 25≤ 10*B25PF/R
≤ 35≤ 15*B35PF/S
≤ 50  ≤ 20*B50PF/XS
≤ 85≤ 50**AR180PF/A
≤ 100  ≤ 100**AR140PF/HA

The new RAUNI regulators are equipped with alarm threshold, which disconnects the equipment if the ALARM THDi is exceeded. Equipments with blocking inductance have this threshold detection disconnected because there is no resonance risk. * Resonance not allowed ** THDv max 6%

Network: 400Vac 50Hz THDi ≤20%.

Resonance not allowed

Capacitors: 550Vac 50Hz, THDi ≤50%


WxDxH, mm


kVAR at


Power of banks













kVAR at 415V

B50PFSXS-15.5 460x215x48015,52,25-4,5-9763RAUNI96221416,5
B50PFSXS-18 460x215x480184,5-4,5-9463RAUNI96261519
B50PFSXS-22.5 460x215x48022,54,5-9-9563RAUNI96321624
B50PFSXS-27 610x215x480274,5-4,5-9-9680RAUNI96392329
B50PFSXS-36 610x215x480364,5-4,5-9-188100RAUNI96522738,5
B50PFSXS-45 610x215x480459-9-9-185100RAUNI96653148
B50PFMXS-63 420x380x920634,5-9-13,5-18-1814125RAUNI96914768
B50PFMXS-76 420x380x920764,5-9-13,5-18-31,517250RAUNI961095182
B50PFMXS-90 420x380x920909-18-27-3610250RAUNI961395497
B50PFMXS-108 420x380x11401089-18-36-4512250RAUNI9615560117
B50PFMXS-135 420x380x11401359-18-36-7215400RAUNI9619469146
B50PFMXS-153 420x380x136015318-36-36-638400RAUNI9622078165
B50PFMXS-180 420x380x136018018-36-54-7210400RAUNI9625988194
B50PFLXS-225 610x610x176022522,5-22,5-45-45-45-4510630RAUNI144324260242
B50PFLXS-270 610x610x176027027-27-54-54-54-5410630RAUNI144388280291
B50PFLXS-315 610x610x196031531,5-31,5-63-63-63-6310800RAUNI144454320339
B50PFLXS-360 610x610x196036036-36-72-72-72-7210800RAUNI144518340388
B50PFLXS-405 610x610x216040540,5-40,5-81-81-81-81101250RAUNI144583380436
B50PFLXS-450 610x610x216045045-45-90-90-90-90101250RAUNI144648400485
B50PFLXS-495 610x610x236049549,5-49,5-99-99-99-99101250RAUNI144713440533
B50PFLXS-540 610x610x236054054-54-108-108-108-108101250RAUNI144778460582
B50PFLXS-630 1220x610x196063063-63-126-126-126-126102x800RAUNI144907640678
B50PFLXS-720 1220x610x196072072-72-144-144-144-144102x800RAUNI1441037680775
B50PFLXS-810 1220x610x216081081-81-162-162-162-162102x1250RAUNI1441167730872
B50PFLXS-900 1220x610x216090090-90-180-180-180-180102x1250RAUNI1441296780969
B50PFLXS-990 1220x610x236099099-99-198-198-198-198102x1250RAUNI14414268301066
B50PFLXS-1080 1220x610x23601080108-108-216-216-216-216102x1250RAUNI14415568801163