ABB B23 and B24

Compatibility

Compatible with EpiSensor Edge over Modbus RTU.

Connect its RS-485 port to a Modbus Interface or to a serial interface on the Gateway. Edge polls it with its Modbus client.

Edge reads 30 values from it, listed under Interface.

Connect it with

• 
  Modbus Interface ZMB-3X
  From €399 ex VAT Configure Modbus Interface
• 
  Gateway ZGW-20
  From €899 ex VAT Configure Gateway

Specifications

Each comes in three functional levels. Steel meters count active energy import only, at Class 1. Bronze meters add export and reactive energy. Silver meters add tariffs, fixed inputs and outputs and resettable registers, and on the B24 can be Class 0.5 S. The communication port is chosen when you order: RS-485, which speaks Modbus RTU or ABB's EQ-Bus, or M-Bus.¹

Power

Self-powered from the measured supply. The meter has no auxiliary supply input and runs from its voltage circuits, which dissipate 1.6 VA (0.7 W) in total.¹

Active energy accuracy

B23: Class B (Class 1); B24: Class B (Class 1) or Class C (Class 0.5 S), EN 50470-3¹

Reactive energy accuracy

Class 2 (IEC 62053-23)¹

Voltage

3 × 230/400 V AC nominal, 3 × 220 to 240 V (-20 % to +15 %)¹

Current (B23)

Direct, 0.25 to 65 A, base current 5 A, starting current under 20 mA¹

Current (B24)

Through CTs, 1 A rated, 6 A maximum; CT ratio 1/9 to 9999/1¹

Frequency

50 or 60 Hz, ±5 %¹

Communication options

RS-485 (Modbus RTU or EQ-Bus) or M-Bus, plus an optical port¹

Legal metrology

MID mechanical class M1, electromagnetic class E2¹

Protection

IP20 at the terminals, IP51 in a protective enclosure¹

Operating temperature

-40 to 70 °C¹

Terminals

B23: 1 to 25 mm² at 3 Nm; B24: 0.5 to 10 mm² at 1.5 Nm¹

Where it is used

• Tenant and departmental submetering, where the MID approval gives a kWh register fit for billing.

  Tenant submetering and cost allocation

• Import and export metering on a solar PV or battery connection, with Bronze or Silver meters.

  Solar PV monitoring

• Metering EV charger circuits up to 65 A with a B23, alongside the rest of the site load.

  EV charging load management

Interface

ABB gives each value's first register in hexadecimal exactly as it goes on the bus, with nothing to subtract. The addresses on this page are the same numbers in decimal: Voltage L1-N at 0x5B00 is 23296.¹

Energy totals are 64-bit counters across four registers. ABB allows reading part of a value, so the map reads the lower two registers of each total as a 32-bit count in 0.01 kWh, which wraps after 42,949,672.95 kWh. Read all four registers if you need the full counter.¹

Powers are signed 32-bit values in 0.01 W, so they top out at about ±21 MW. A missing value reads as all ones if unsigned, or the highest positive number if signed.¹

Setup

1. Check the port

   Meters with RS-485 have three communication terminals, A, B and C; M-Bus meters have two. Only the RS-485 meters speak Modbus.¹

2. Choose Modbus

   In the meter's RS485 settings, set the protocol to Modbus rather than EQ-Bus, then set the baud rate from 1200 to 115200 bit/s, an address from 1 to 247 and the parity. Set Edge to match.¹

3. Wire the bus

   Connect A, B and C to a ZMB-31 or the Gateway's serial interface. The communication terminals take 0.5 to 1 mm² wire at 0.25 Nm.¹

4. Set the CT ratio on a B24

   Enter the current transformer ratio, from 1/9 to 9999/1, in the meter's ratio settings before you rely on any current, power or energy reading.¹

5. Read one register

   Import the template and read Voltage L1-N at 23296 (0x5B00) with function code 3. It is an unsigned 32-bit value in 0.1 V steps, so 2301 means 230.1 V.¹

6. Enable the map

   Once voltage, current and total active power match the display, enable the rest of the map and watch several fresh readings before you add exports or alarms.

Common questions

Which B23 and B24 meters have Modbus?

Those with an RS-485 port, set to the Modbus protocol in the meter's RS485 settings. The same port can speak ABB's EQ-Bus instead. Meters ordered with M-Bus do not speak Modbus.¹

What is the difference between the B23 and the B24?

The B23 is direct connected up to 65 A. The B24 is transformer connected, rated 1 A with a 6 A maximum on the secondary, with a configurable CT ratio, and can be Class 0.5 S.¹

Why do the export registers read FFFF?

Steel meters count active import only and have no export registers. A value the meter does not have reads as all ones if unsigned.¹

What are the Modbus RS-485 settings?

Address 1 to 247; 1200, 2400, 4800, 9600, 19200, 38400, 57600 or 115200 bit/s; no, odd or even parity. Reads use function code 3, for 1 to 125 registers at a time.¹