MCM-Inst-1.10
Page 5 of 27
D
From the overcurrent protection to
the step-down transformer (N, L1)
277V tap to the AC/DC power supply
1-Phase, 2-Wire 277V with neutral
3-Phase, 4-Wire 277V/480Y with neutral
E
From the fuse to the step-down
transformer (L1, L2) 600V tap to the
AC/DC power supply
3-Phase, 4-Wire 347V/600Y with neutral
3-Phase, 3-Wire 600V Delta (no neutral)
<Comm>
- The communication type. The MCM does not support both RS-485 and Ethernet in one
model.
●
MB
- Modbus RTU using RS-485
●
MBT
- Modbus TCP using Ethernet and TCP/IP
<Enclosure>
- The enclosure field specifies one of the following enclosure options:
●
ME3
- Steel NEMA 4 enclosure, 12 to 48 CTs, 12 in. × 12 in. × 6 in.
●
FE1
- Fiberglass NEMA 4X enclosure, 12 to 48 CTs, 12 in. × 12 in. × 6 in.
●
ME4
- Steel NEMA 4 enclosure, 60 to 84 CTs, 16 in. × 14 in. × 6 in.
●
FE2
- Fiberglass NEMA 4X enclosure, 60 to 84 CTs, 16 in. × 14 in. × 8 in.
<Protection>
- The protection field specifies the overcurrent protection as one of the following:
●
C
- Three-phase circuit breaker, rated up to 480 Vac; also acts as a disconnect.
●
F
- Three-phase fuse block, rated for 600 Vac; typically used with voltage group E. The fuse holder
is not rated for use as a disconnect.
●
N
- No circuit protection. The MCM provides field wiring terminal blocks in place of the circuit
protection. An external disconnect and overcurrent protection are required.
Opt <Options>
- Some models may include additional options, such as
Opt EP
, to configure the
MCM for even parity communications. See the datasheet for all options.
The four most common models follow:
●
MCM24-A-MB-FE1C
- 24 CTs, 120 - 240 Vac, fiberglass enclosure, circuit breaker
●
MCM24-A-MB-ME3C
- 24 CTs, 120 - 240 Vac, steel enclosure, circuit breaker
●
MCM72-A-MB-FE2C
- 72 CTs, 120 - 240 Vac, fiberglass enclosure, circuit breaker
●
MCM72-A-MB-ME4C
- 72 CTs, 120 - 240 Vac, steel enclosure, circuit breaker
2.2 Multi-Circuit Metering
The CCS MCM is organized into multiple three-element (or three-phase) submeter blocks (SMB).
Each SMB behaves as an independent meter, with a different Modbus address. For example, an
MCM12-A-MB-FE1C supports twelve current transformers and contains four SMBs, each with three
CT inputs. This design has several implications.
●
Each submeter block has the same Modbus register list as a regular WattNode
®
meter.
●
The SMBs’ Modbus addresses start with the primary SMB’s address (ADDR+0) and increments
by one for each SMB (ADDR+1, etc.). The address can be configured with the DIP switch or using
the
Address
Modbus register.
●
Communication settings can only be changed on the primary submeter (ADDR+0) and will auto-
matically cascade to all other SMBs in the MCM.
●
All SMBs use the same baud rate and parity settings.
●
The sum and average registers will only sum or average the metering elements within a single
SMB. Readings from different SMBs can be combined externally.
●
Each SMB independently measures the line voltages and line frequency, so the reported values
will differ slightly from one submeter to another.
●
The SMB readings will not always update simultaneously.
