SN-NM-A1 automatic arc suppression coil tuning controller
The automatic controller retunes the arc suppression reactor to the resonance point in less than 1 s when the network capacitance changes. It works with reactors of any type and outputs an earth fault signal and network parameters.
- Measurement method
- Locus Measurement (two-point resonance curve measurement)
- Reactor tuning time
- < 1 s
- Earth fault signal threshold (default)
- 30 % neutral displacement
- Monitored network parameters
- damping d, asymmetry k, detuning v, harmonics
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Description
Automatic Tuning Device SN-NM-A1 is an automatic tuning controller for an arc suppression reactor. Resonant earthing is used mainly in overhead networks, where most faults are single-phase earth faults, often temporary. The Petersen coil reduces the fault current below the self-extinguishing level (less than 35 A), so temporary faults disappear without tripping the feeder. For this, the reactor inductance must match the current network capacitance (IL = IC). The capacitance changes when feeders are switched on and off, when overhead lines are replaced by cable and so on, so the controller continuously monitors the network and retunes the reactor to the resonance point.
It is based on the Locus Measurement method, a two-point measurement of the neutral voltage resonance curve. It gives fast and accurate tuning in any weather, including with floating neutral displacement in bad weather, when the risk of a fault is highest. The controller tunes the reactor in less than 1 s, works with arc suppression reactors of any type, in networks with several controllers and in very symmetrical cable networks, and can remotely control the neutral earthing resistor. The device continuously outputs network parameters, namely damping, asymmetry, detuning and harmonics. It also outputs an earth fault signal (by default at a neutral displacement of 30 %), including detection of high-resistance faults.
The controller is operated from the local panel (LCD display, up/down buttons, manual and automatic modes, group alarms Threshold and Fault), from a PC with the NMTerm program supplied in the kit, or remotely through wired signals, by protocol through a serial or network port and with a modem. The program works in several languages. An event log is kept. For networks with very low asymmetry there is a U0 injector in the control cabinet, which increases the neutral displacement for accurate tuning and has passive overload protection.
The hardware includes analog inputs of 0–110 V, analog outputs of 0–20 mA (reactor position) and 0–16–20 mA (neutral voltage), digital inputs of 24–110 V or 110–220 V DC, and output relays up to 250 V. Power supply is 90–230 V AC/DC, interfaces are Ethernet, RS-232 and CAN. The controller is available in two versions, namely a separate 19″ rack in the substation building or built into the reactor cabinet. Together with the fault locator it forms a complete capacitive current compensation system.
Technical specifications
| Measurement method | Locus Measurement (two-point resonance curve measurement) |
|---|---|
| Reactor tuning time | < 1 s |
| Earth fault signal threshold (default) | 30 % neutral displacement |
| Monitored network parameters | damping d, asymmetry k, detuning v, harmonics |
| Analog inputs | 0–110 V AC |
| Analog outputs | 0–20 mA (reactor position), 0–16–20 mA (neutral voltage) |
| Digital inputs | 24–110 V DC or 110–220 V DC |
| Power supply | 90–230 V AC/DC |
| Interfaces | Ethernet, RS-232, CAN, modem, telemechanics protocols |
| Software | NMTerm (Rus., Eng., Ger., Swe., Cze., Por.) |
| Versions | in a 19″ rack or built into the reactor cabinet |
Request a price and lead time
SN-NM-A1 automatic arc suppression coil tuning controller. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
In what time does the controller tune the reactor?
In less than 1 s. It works by the Locus Measurement method, that is, a two-point measurement of the neutral voltage resonance curve.
What power supply and interfaces does SN-NM-A1 have?
Power supply 90–230 V AC/DC, interfaces Ethernet, RS-232 and CAN, as well as a modem. Setup is done with the NMTerm program.
Which network parameters does the device output?
Damping, asymmetry, detuning and harmonics. The earth fault signal is by default given at a neutral displacement of 30 %.
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