NER — neutral earthing resistor up to 70/√3 kV
Neutral Earthing Resistor (NER) — a neutral earthing resistor for medium-voltage networks.
- Voltage
- up to 70/√3 kV
- Current
- up to 100 A (higher on request)
- Duty
- continuous or short-time (10 s)
- Cooling
- ONAN; AA or AFA
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Neutral Earthing Resistor (NER) — a neutral earthing resistor for medium-voltage networks. The resistor is usually connected to the transformer neutral and creates the active current component required by traditional earth-fault protections for reliable and selective detection of a single-phase fault. In networks with arc suppression coils, the resistor is switched in for a short time in parallel with the reactor so that directional feeder protections can operate. The manufacturer produces four types: NER connected through a single-phase transformer; NER connected through an earthing transformer; NER connected to the auxiliary winding of an arc suppression coil (including the oil-free version); primary NER connected directly to the neutral. The resistive elements are made of stainless steel with air cooling; the resistor is equipped with built-in overload protection, a local control panel with a remote/local switch and a remote control interface. The single-phase and earthing transformers in the resistor assemblies have a sealed design; built-in voltage and current transformers are supplied optionally. Versions are available for indoor and outdoor installation, with Elastimold, DIN or Pfisterer cable bushings. Technical characteristics: voltage up to 70/√3 kV, current up to 100 A (higher values on request), continuous or short-time operation of 10 s, ONAN or AA/AFA cooling, frequency 50 or 60 Hz, auxiliary winding 690 and 345 V, insulation per IEC 60076-3, temperature −40…+40 °C. Examples of implemented products: a resistor connected to an 11 kV/√3 earthing transformer, 15 A, 30 s, and a primary resistor 22 kV/√3, 600 A, 10 s. The products are manufactured in cooperation with a German plant — one of the largest transformer manufacturers in Europe. The manufacturer has supplied neutral earthing resistors since 1991 to customers in Sweden and other European countries; the remote switching of the NER can be controlled by the automatic arc suppression coil tuning controller SN-NM-A1.
Technical specifications
| Voltage | up to 70/√3 kV |
|---|---|
| Current | up to 100 A (higher on request) |
| Duty | continuous or short-time (10 s) |
| Cooling | ONAN; AA or AFA |
| Elements | stainless steel, air cooling |
| Frequency | 50 or 60 Hz |
| Auxiliary winding | 690 V and 345 V |
| Temperature | −40…+40 °C |
| Versions | with single-phase transformer, with earthing transformer, with arc suppression coil, primary NER |
Replacement for
no direct analogue; neutral earthing resistors 6–35 kV (general type)
selected by purpose and main parameters, please confirm with our manager
Request a price and lead time
NER — neutral earthing resistor up to 70/√3 kV. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
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