CB
Circuit breaker
CBM
Combined backplane module
CCITT
Consultative Committee for International Telegraph and
Telephony. A United Nations-sponsored standards body
within the International Telecommunications Union.
CCM
CAN carrier module
CCVT
Capacitive Coupled Voltage Transformer
Class C
Protection Current Transformer class as per IEEE/ ANSI
CMPPS
Combined megapulses per second
CMT
Communication Management tool in PCM600
CO cycle
Close-open cycle
Codirectional
Way of transmitting G.703 over a balanced line. Involves
two twisted pairs making it possible to transmit
information in both directions
COM
Command
COMTRADE
Standard Common Format for Transient Data Exchange
format for Disturbance recorder according to IEEE/ANSI
C37.111, 1999 / IEC 60255-24
Contra-directional
Way of transmitting G.703 over a balanced line. Involves
four twisted pairs, two of which are used for transmitting
data in both directions and two for transmitting clock
signals
COT
Cause of transmission
CPU
Central processing unit
CR
Carrier receive
CRC
Cyclic redundancy check
CROB
Control relay output block
CS
Carrier send
CT
Current transformer
CU
Communication unit
CVT or CCVT
Capacitive voltage transformer
DAR
Delayed autoreclosing
DARPA
Defense Advanced Research Projects Agency (The US
developer of the TCP/IP protocol etc.)
DBDL
Dead bus dead line
DBLL
Dead bus live line
DC
Direct current
Section 8
1MRK 511 418-UEN A
Glossary
40
650 series 2.2 IEC
Communication protocol manual