Janitza UMG 103

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 32 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

The UMG 103 is a compact power analyser from Janitza for building installations, distribution boards, circuit breakers and busbar trunking. It clips onto a 35 mm DIN rail in any position, takes four module widths and works in TN and TT systems. It measures up to 240 V phase to neutral directly, with voltage transformers above that, and reads current through x/1 A or x/5 A transformers or directly up to 5 A.¹

Power

Self-powered from the measured supply. Taken from the L1-N, L2-N and L3-N measuring inputs: 115 to 240 V from one phase or 80 to 240 V from three phases (±10 %), 45 to 65 Hz, 4 VA at most. At least one phase must be above 100 V, and it rides through outages of up to 80 ms at 230 V.¹

Active energy accuracy

Class 0.5S (EN 62053-22) and Class B (EN 50470-3) with x/5 A CTs; Class 1 and Class A with x/1 A CTs¹

Reactive energy accuracy

Class 2 (EN 62053-23)¹

Measurement classes (IEC 61557-12)

Voltage 0.2, current 0.5, active power 0.5, frequency 0.1¹

Voltage inputs

Up to 240 V L-N and 415 V L-L, 300 V CAT III¹

Current inputs

x/1 A or x/5 A transformers, 5 A nominal, 6 A continuous¹

Harmonics

Odd orders from the 1st to the 25th, voltage and current, with THD¹

Modbus address

1 to 99, on two rotary switches¹

Dimensions

71.5 × 98 × 46 mm, 150 g, 4 DIN modules¹

Protection

IP20¹

Operating conditions

-25 to 60 °C, 5 to 95 % RH non-condensing¹

Where it is used

• Outgoing feeders and sub-distribution boards on existing 1 A or 5 A current transformers, where a small meter with no display is enough.

  Transformer and distribution board monitoring

• Harmonic and THD monitoring on circuits with drives, UPS systems and IT loads.

  Data centre power monitoring and PUE inputs

• Adding energy and power quality readings to a BMS or SCADA system through Edge.

  Modbus meter integration for a BMS or SCADA system

Interface

The addresses on this page are Janitza's big-endian addresses, sent on the bus as they are. Janitza also publishes a little-endian copy of the list at a higher address; do not mix the two.²

The meter has no display to compare against. Check the first readings with a clamp meter or a panel meter on the same circuit.¹

Setup

1. Set the address

   Turn the two rotary switches (tens and units) to a unique address from 1 to 99 before power-up. Address 00 starts the boot loader, not the meter.¹

2. Wire the bus

   Run shielded twisted pair from A and B to a ZMB-31 or the Gateway's serial interface, with up to 32 devices per segment and 1,200 m at 38.4 kbit/s. Fit 120 Ω resistors at both ends of the segment: the meter has none built in. Janitza says CAT cable is not suitable.¹

3. Match Edge to the meter

   Set Edge to 8 data bits, no parity and 1 or 2 stop bits, at any rate from 9600 to 115200 bit/s. The meter detects the baud rate itself.²

4. Set the CT ratio

   The meter leaves the factory set to 5/5 A. Set the real primary and secondary current with GridVis over RS-485 before you trust any current, power or energy reading.¹

5. Read one register

   Import the template and read Voltage L1-N at address 19000 with function code 4. With no display on the meter, compare it with a handheld meter on the same supply.²

6. Enable the map

   Once voltage, current and total power agree with your reference, enable the rest of the map and watch several fresh readings before you add exports or alarms.

Common questions

Which baud rate does the UMG 103 use?

It detects the rate automatically: 9600, 19200, 38400, 57600 or 115200 bit/s. Framing is 8 data bits, no parity and 1 or 2 stop bits.^1, 2

How do I set the current transformer ratio?

Over RS-485 with Janitza's GridVis software. The meter ships set to 5/5 A, so current, power and energy read wrong until you enter the real ratio. A summation transformer counts as the sum of its primaries, such as 2000/5 A for two 1000/5 A transformers.¹

Does the UMG 103 need its own power supply?

No. It runs from its voltage measuring inputs and needs at least 100 V on one phase to neutral. That also means it loads voltage transformers with a non-linear current, so Janitza calls it only conditionally suitable for medium and high-voltage systems.¹

Which function codes does the UMG 103 support?

FC03 and FC04 to read, FC06 and FC16 to write, and FC23 to read and write in one request. The Edge template reads with FC04 only.²