Energy meter with detachable display designed for retro-fit

Kits comprising a compact energy meter and three split-core current sensors offer the simplest route to add energy metering in existing installations

Carlo Gavazzi has introduced a new version of its innovative EM21-72 compact energy meter, which is designed specifically for retro-fit applications. EM21-72R is an innovative and cost-effective energy meter with a detachable display, which can be mounted either on a panel with just 72x72mm footprint, or on a DIN-rail in only four modules. No further adaptors or external accessories are required: current measurements are carried out via external miniature current sensors, included with the meter.

Current sensors use a split core technology, so no wiring modifications are needed and there is no need to disconnect cables during installation. The CTs are available in 3 different ranges: 90A with 10mm hole diameter; 150A, hole diameter 16mm; and 250A, hole diameter 24mm.

As a result, the kit offers the simplest and easiest way to introduce an energy measuring system in older buildings and existing installations, without modifying or disconnecting any wiring. Installation is faster and simpler, thanks to the meter’s self-power supply, automatic phase detection with wrong-phase-sequence warning, and fast application-oriented programming procedure.

To provide a ready-to-install package for all retro-fit requirements, the EM21-72R is available in three ranges covering currents up to 250A. Seven sets of three variables can be selected for display, providing for active and reactive energy measurement or a complete set of variables. Options include: system variables such as W, var, PF, Hz and phase-sequence; single-phase variables including A, VLL, VLN, PF; TRMS measurements of distorted sine waves; and energy measurements (total kWh and kvarh).

As standard, a pulse output provides fast and easy data transmission to PCs and PLCs for full load control, whilst all electrical parameters of the installation can sent via the optional RS-485 port for integration with BMS (Building Management Systems) and other standard acquisition-monitoring systems.

Instantaneous variables are displayed as 3 x 3 digits, with energy meter readings to 6+1 digit resolution. Accuracy is ±0.5% RDG (V, A), and the meter is rated Class B according to EN50470-3 (class 1 of EN62053-21), Class 2 (kvarh) according to EN62053-23. Operating temperature range is from -25°C to +55°C and the front panel offers IP50 protection against dust and water ingress.