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Transmitters for electricity energy monitoring (AC)

Need to know how energy on your site is used in detail? Eltek Gen II transmitters and ND sub metering systems provide the solution.


  • Load balancing
  • PF correction
  • Optimise energy distribution
  • Save costs
  • Efficiency planning
  • Alarm reporting
Sensors are not included and must be ordered separately.
GD90A The GD90A interfaces with the Northern Design NDRail350 (1 x 3 phase load) or NDRail310 (3 x single phase load) energy meters, providing comprehensive monitoring and patterns of use of a three phase supply. Information recorded:
  • 3 x Current (up to 100A) phases
  • 3 x power factor
  • 1 or 3 Voltage phase
Calculated values transmitted or derived for: kVA, kVAr and kW.
Internal battery back-up. Requires 12VDC e.g. DRA18-12 power.
GD900A The GD900A can be used with up to six parallel connected NDRail310 or NDRail350 energy meters and appropriate current transformers, providing comprehensive monitoring and patterns of use of multiple three phase supplies.


Current transformer (one per phase) with 1m lead - other types available POA:
Type Range Size (mm) Cable dia  
SCL8-5 0-5A 43 x 37 x 32
SCL16-50 0-50A 51 x 45 x 27 16mm
SCL16-100 0-100A 51 x 45 x 27 16mm
SCT19-150 0-150A 51 x 53 x17 19mm SCT closed SCT open
SCT32-400 0-400A 82.5 x 85 x 27 32mm
SCT51-800 0-800A 121 x 127 x 32 51mm
Other SCT19 models available: 5, 10, 15, 20, 30, 50, 70 and 100A - refer to Eltek
Other SCT32 models available: 70, 100, 150, 200, 250, 300, 400 and 600A - refer to Eltek
Other SCT51 models available: 600, 1000A - refer Eltek
DRA18-12 DIN rail mounting AC to 12VDC power supply
NDRail350 DIN rail mounting energy meter
(1 x 3 phase load)

NDRail310 DIN rail mounting energy meter
(3 x 1 phase loads)

See for more information.



Common Specification

RF specification: EN300-220
RF power: 10mW
Environment specification  
  Compliant to EN300-220: -10 to +55°C
  Actual: -30 to +65°C
  Humidity: 100% non condensing
Environmental rating: IP40
Dimensions (footprint): 78 x 41mm
Battery endurance: up to 5 years (interval set to 5 minutes) (less for GL-70 and GS40 series)
Transmission interval range: 1 sec to 4 hours
Indicator (red LED): transmit active/on/off
Control switch (concealed): test mode / hibernate
Antenna socket: SMA

Transmitter Specification

Model(s) Sensors Range
GD90A 1 x RS485 modbus input for NDRail310 or NDRail350 energy meter 3 x Current (up to 100A) phases
3 x power factor
1 or 3 Voltage phase
Calculated values transmitted or derived for: kVA, kVAr and kW
GD900A As GD90A but can connect to up to 6 x NDRail310 or 6 x NDRail350 meters  

NDRail350 Specification

Isolation: Fully isolated
Actual range: Voltage 50% to 120%, current 0.2% to 120%
Frequency range: 45 to 65Hz ( up to 30th harmonic at 50Hz)
Burden per phase: Voltage or current <0.1VA
Accuracy (voltage or current): To class 0.1 IEC60688
Max Current: Direct mode (not using CT) max current is 5A (operating under installation category II(IEC 61010-1)
Indirect mode (using appropriately rated CT) up to 1000A
Dimensions: 106 x 90 x 58mm (DIN rail mounting)
Display: All values can be viewed via built in LCD and button panel


Common to all transmitters
Gen II Quick Start Instructions

Specific to this family of transmitters
Energy Monitoring Leaflet
Energy Monitoring Multidrop Leaflet

User Instructions
GD90A User Instructions
GD900A User Instructions