The digital power and energy meter AD-LU 20 GT measures all standard values of the three-phase system (active-, reactive-, apparent-power, voltage, currents, harmonics, power factor etc.) and provides this via an Ethernet interface. The measured values can be read out via Modbus-TCP protocol. In addition, these measured values are displayed on an integrated small WEB server. The device can also be parameterized via this WEB server. The AD-LU 20 GT is also equipped with an RS485 interface. This RS485 interface with Modbus-RTU protocol is mainly suitable for connecting an external display (AD-MM 400), but can also be used to read data or parameterize. The current is fed via the front-mounted through-current converters, which can measure up to 20 A directly. However, additional current transformers for larger currents can also be connected at any time. It is possible to measure symmetrical or unbalanced 4-wire networks and symmetrically loaded 3-wire networks. Due to the integrated, efficient wide-range power supply, the device operates in a large supply voltage range and does not heat up very much.



Measurement and monitoring of all electrical characteristics in electrical systems. Detection of load profiles for energy management systems, e.g. ISO 50001. Recording the energy consumption of individual consumers. Monitoring of voltage quality variables, e.g. harmonics.

Specific characteristics

  • internal current-transformer
  • Ethernet-Interface
  • RS485-Interface
  • Counters for active, reactive and apparent energy
  • Counters for purchased or fed energy

Business data

Order number
AD-LU 20 GT Power meter
AD-MM 400 Compatible display
AD-VarioPass3 USB/RS485-adapter
EClass 27210124
Customs tariff number / country of origin 8543 70 90 / Deutschland


Data sheet pdf en-lu20gt.pdf (315 kB)
Tender text zip (19 kB)
STEP file step gt4a.step (6 MB)
Safety instructions pdf ad-safety-instructions.pdf (43 kB)

Technical specifications

Current-inputs (I1...I3)
Measuring ranges 0 ... 1 A AC; 0 ... 5 A AC;
0 ... 20 A AC
Max. conductor diameter 4,8 mm
Voltage-inputs (L1...L3)
Measuring range 50 ... 253 V AC
Input resistance Ca. 950 kOhm
Software protocol Modbus-TCP
Network mask
WEB-Server Port 80
Software protocol Modbus-RTU
Data format 19200, e, 8, 1
Max. bus users 99
Bus termination 120 ohms both sides at the end
Max. length of bus 500 m (no stubs)
Cable Twisted and shielded
Voltage range AC 50 ... 253 V AC, 50/60 Hz (see voltage-inputs)
Nominal voltage AC 230 V AC
Power consumption Max. 2,5 VA
Transfer behavior - in reference to the current value
Basic accuracy < 0,5 % (class 0.5)
Temperature influence 80 ppm/K
Response time < 0,5 s
Dimensions (WxHxD) 71x90x70 mm
Type of protection IP 20
Connection method Screw clamp
Terminals, wire cross section 2,5 mm² flex wire / 4 mm² one wire
Bolting torque terminals 0,6 Nm
Skinning length 6 mm
Weight ~ 180 g
Manner of fastening 35 mm DIN rail 35mm
Environmental conditions
Ambient temperature -10 ... 50 °C
Storage and transport -10 ... 70 °C (no condensation)
Product family standard EN 61326-1 1)
Emitted interference EN 55011, CISPR11 Cl. B, Gr. 1
Electrical safety requirements
Product family standard EN 61010-1
Overvoltage category II
Pollution degree 2
Safety measurement EN 61010-2-030
Measurement category CAT III
Galvanic isolation, test voltages
Grid side to RS485-Bus 4 kV, 50 Hz (1 min.)
Grid side to control elements 4 kV, 50 Hz (1 min.)
Protection circuits
Input Electrical surge protection
RS485-Bus Electrical surge protection
Power supply Protection against over-temperature, over-voltage and over-current
1) During checking, slight signal deviations are possible.

Block and wiring diagram




We only use technically necessary cookies to improve the user-friendliness of our site.
Cookies for analysis and marketing purposes are not used!
You can find further information in our privacy policy.
made with ♡ by