Novatech Bitronics M87X Series, Manual

Page: 109 / 184

ML0021 August 15, 2018
93
Copyright 2018 Bitronics, LLC
7.4 Current Input (CT) Connections
The current input terminal block for units with internal CTs features 10-32 terminals (M871)
or 8-32 screws (M872) to assure reliable connections. Current from the inputs flow
through the current transformers via #12 AWG SIS, 600V wire, and crimped ring-lugs with
brazed seams. This results in a robust current input with negligible burden to ensure that
the user’s external CT circuit can never open-circuit, even under extreme fault conditions.
The M871 has four independent current inputs, one for each phase being measured, plus
neutral while the M872 has 6 independent current inputs for two sets of three-phase
measurement. Current signals are connected directly to #10-32 studs (M871) or #8-32
screws (M872) on the current input terminal block on the front of the Signal Input module.
See Section 7.3 for connection recommendations. It is intended that the instrument
connect to the output from the secondary of permanently installed Current Transformers
(CTs).
Grounding of CT signals per ANSI/IEEE C57.13.3-1983 is required. The current
input terminal block
For the M871 and M872 with split-core CTs, external split core CT secondary wires
connect to the current terminal block
.
The current inputs for this model are touch safe. No
internal current isolation is provided within the meter. DO NOT CONNECT Hazardous
Live voltages to the current input terminal block. Only connect the external Split Core CT
secondary current outputs to the meter’s current input terminal block. Isolation is provided
from the external Split Core CTs. Recommended torque is 9 In-Lbs, 1.02 N-m
Signal Input Module S1C Used with Split-Core CTs on M871