Page 4 of 27 MCM-Inst-1.10
2 Overview
Congratulations on your purchase of the Multi-Circuit Meter for Modbus
®
(MCM) watt/watt-hour meter.
The MCM can measure 100 to 600 Vac, single-phase and three-phase, wye and delta services. It
supports demand-side management (DSM), submetering, energy monitoring, billing, and renewable
energy applications.
There are two communication versions of the MCM:
●
MCM...MB...
- Communicates using Modbus RTU over EIA RS-485 two-wire twisted-pair links.
●
MCM...MBT...
- Communicates using Modbus TCP over Ethernet TCP/IP networks.
The MCM meets the revenue metering ANSI C12.1 Class 1 standard when used with class 0.6 current
transformers (CTs) and meets ANSI C12.20 Class 0.5 with class 0.2 or class 0.3 CTs.
The MCM includes the multi-circuit meter, a NEMA rated enclosure, a DC power supply, circuit protec-
tion (fuses or circuit breaker), and terminal blocks, all prewired as a UL 508A Listed industrial control
panel, ready for mounting.
2.1 Model Number Scheme
The MCM is available with many different model numbers. The following section explains how to
decode the MCM model numbers.
MCM<NumCTs>-<VoltageGroup>-<Comm>-<Enclosure><Protection> Opt <Options>
<NumCTs>
- The number of CTs (or current sensors), which may be 12, 24, 36, 48, 60, 72, or 84. For
example:
MCM12
. Each submeter in the MCM has three CT inputs, so the number of submeters will
be the number of CTs divided by three: 4, 8, 12, 16, 20, 24, or 28.
<VoltageGroup>
- The measurement circuitry on all MCM models can measure 100 to 600 Vac, but
the power supply configuration depends on the electrical service type. The voltage group (
A
,
B
,
C
,
D
, or
E
) selects the appropriate configuration. See the table below to verify that the voltage group
matches your electrical service type. If possible, choose from the bold entries in the table below as
they are the most common.
Table 1: MCM Voltage Groups
Voltage
Group
Power Wiring Description
Supported Electrical Service Types
A
Direct from the overcurrent pro-
tection to the AC/DC power supply
(N, L1)
1-Phase, 2-Wire 120V with neutral
1-Phase, 3-Wire 120/240V
3-Phase, 4-Wire 120V/208Y
1-Phase, 2-Wire 230V with neutral
3-Phase, 4-Wire 230V/400Y
3-Phase, 4-Wire Delta 120/208/240V with neutral
3-Phase, 4-Wire Delta 240/415/480V with neutral
B
Direct from the overcurrent protec-
tion to the AC/DC power supply (L1,
L2)
1-Phase, 2-Wire 208V (no neutral)
1-Phase, 2-Wire 240V (no neutral)
3-Phase, 3-Wire 208-240V Delta (no neutral)
1-Phase, 3-Wire 120/240V
3-Phase, 4-Wire 120V/208Y
3-Phase, 4-Wire Delta 120/208/240V with neutral
C
From the overcurrent protection
to the step-down transformer (L1,
L2) 480V tap to the AC/DC power
supply
3-Phase, 4-Wire 277V/480Y with neutral
3-Phase, 3-Wire 400V Delta (no neutral)
3-Phase, 3-Wire 480V Delta (no neutral)
3-Phase, 4-Wire 230V/400Y
3-Phase, 4-Wire Delta 240/415/480V with neutral
