Technical Parameters

Type UNL1-E (Electronic) UNL1-M (Electro – Mechanical)
No of poles 2,4 2,4
 Product appearance 

 Rated currentInA 25,32,40,63 25,32,40,63
 Rated residual current  I∆ Ma 30,100, 300 30,100, 300
 Tripping range I∆Ma 0,5-1 x I∆n 0,5-1 x I∆n
 Rated frequency Hz 50-60 50-60
 Type class AC AC
 Rated voltage Ue V Ac 240 240
 Rate insulation voltage Ui V 660 660
 Rated impulse withstand voltage Uimp Kv 6 6
 Rated short circuit capacity A 6000 6000
 Electrical life Ope. V 230 4000 4000
 Mechanical life Ope 20000 20000
 Degree of protection IP 20( IP 40) IP 20( IP 40)
 Ambient operational temperature ℃ -25 / +40 -25 / +40
 Storage temperature ℃ -40 / +55 -40 / +55
 Fixing (en 60715) 35mm DIN rail 35mm DIN rail
 Connection cross section (min/max) Mm² 1,5-35 1,5-35


Union RCCB’s are designed to protect equipment and people from low level ground faults. Typical applications include resistance and impedance heating systems; submersible pumps; semiconductor process equipment and wet location equipment.
The RCCBs use the residal current sensing method to detect ground faults. The units monitor the load currents and will trip immediately should they detect any imbalance greater than the rated trip level. Union RCCB’s derive the energy required to trip
from the ground fault current alone. They will operate normally even if the system voltage drops or if the neutral wire is disconnected. They will also operate normally. during long periods of over voltage.


30mATripping current designed for additional protection against direct contact, the 30 mA RCCB protects against leakage currents and indirect contact with earth loop impedance up to 1667 Ohms; for use as additional protection against direct contact, residual tripping current must not exceed 30 mA.
300mAA lees sensitive protection suitable for large installations having high levels of leakage current: 300 mA RCCB’s protect against leakage current and indirect contact up to 167 ohms earth loop impedance

Working Principle

RCCB works on the principle that in an electrical circuit the incoming current is the same as out going current as shown in the diagram. RCCB incorporates a core balance transformer having primary and secondary windings and a sensitive relay for instantaneous detection of fault signal. The primary winding lies in series with the supply mains and load. Secondary winding is connected to a very sensitive relay. In a faultless situation, the magnetized effects of the current carrying conductors cancel each other out. There is no residual magnetic field that could induce a voltage in the secondary. During flow of leakage current in the circuit an imbalance is created in the circuit which gives rise to leakage flux in the core. This leakage flux generates and electrical signal that is sensed by the relay and it trips the mechanism thereby disconnecting the supply. When pressing the TEST button ‘T’, a fault is simulated via the test resistance & RCCB trips.

Residual Current Protection in The Event of Direct Contact

To provide extra protection in the event of direct contact with an (unearthed) live part, extremely sensitive RCCB’s with rated residual operating current of 30mA or less (IΔ=30mA) are used instead of more conventional RCCB’s with higher residual operating fault currents.

This Extra Protection Is Necessary If

  1. The insulation of totally insulated devices or their loads are damaged.
  2. The earth wire is interrupted.
  3. The earth wire and live wire are transposed (accidentally thus rendering line the body of a protection class I device).
  4. A component which is live in normal operation is touched during repair work. In view of this increased range of protection, an RCCB or RCCB/MCB with IΔ=30mA is must-by law in some European countries to be used when Installation machinery of equipment in areas with particularly high accident risk.
  5. Socket-outlet power circuits in rooms with bath or shower.
  6. Caravans, boats and yachts and their power supply on camping or berthing sites.
  7. Electrical appliances in rooms used for medical purposes.The drawn-in switch-off characteristics of residual current devices with a rated fault current of 10 and 30mA make it clear that the residual current devices are able to prevent the occurrence of the dangerous heart chamber fibrillation. For this reason residual current circuit breakers with rated fault currents of 10mA are used for the protection of particulary exposed individual equipment.
    Residual current circuit breakers with 30mA rated fault current are already specified today for many areas(bath, medically utilized rooms outside areas, agriculture, etc.) in order to ensure the protection of persons.

Residual current protection in the event of indirect contact

To ensure that the RCCB switches off the protected circuit immediately. If there is an insulation fault causing a short-circuit to an exposed part(frame etc.) of machinery and equipment(protection against indirect contact), the maximum permissible touch voltage UT must occur at a residual current greater than or equal to the rated residual operating current lm that triggers the RCCB. This condition is met by earthing the exposed part with a sufficiently low resistance to earth RE.

Earth resistance R E

< Touch voltage U TRated residual operating current-I M

Touch Voltage(U,V)Earth Resistance R E Sevinsitivity I M (mA)
 30 100 300
 25 833 250 83
 50 1666 500 1600
 65 2160 650 216

Permissible earth resistance (R E ) with Max. permissible touch voltage (U T).

Protection against hazardous shock currents

  • Protection against indirect contact (indirect personnel protection). Protection is provided by disconnecting hazardous high touch voltages caused by a short circuit to exposed conductive parts of equipment.
  • When using RCCBs with I∆n ≤ 30 mA, protection from direct contact (direct personnel protection) is also provided. Supplementary protection measure by disconnection when live parts are touched.

The Installations Standards

RCCBs may be used in all three distribution network types (DIN VDE 0100 Part 410) and in an IT network system provided that the capacity of the network to ground is sufficient to allow a fault current to flow which has the same level as the rated fault current. The IT network can still be monitored using an insulation monitor. Both protective systems do not mutually interfere with one another.

Circuit Connection

Protection against transient currents

In order to avoid nuisance tripping (unwanted tripping due to an impulse voltage) due to lightning surges, switching on high capacitance circuits and switching surges, Rcd’s series have a high level of immunity to transient currents.

Lockable Terminal For Additional Protection