Crown Boiler MWC Series Specifications download pdf (Page 154)

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units

140

b) All analog signals for control purpose shall be acquired, validated,

processed and their respective data base updated at a maximum

interval of 250 milli-seconds except for some fast-acting control

loops for which the above-referred time shall be as per process

requirement. For signals required for information only, the above

functions shall be performed at an interval of within 1 second.

c) The 4-20 mA input analog cards shall be suitable for interfacing

transmitters giving 4-20mA analog signal along with superimposed

HART interface signals. 4-20 mA DC signal will only be used for

control purpose and superimposed HART signal will be used for

configuration, maintenance diagnostic and record keeping facility for

electronic transmitters and analysers etc. For non-HART 4- 20mA

analog inputs, conventional non-HART AI module shall be applied.

ii) Binary Signal Conditioning & Processing

a) The changeover type contacts (i.e. 'NC' + 'NO' together) shall be

wired to the control system for all the binary inputs required for

control purposes, except for inputs from MCC/switchgear, actuators

and inputs related to hardwired signal exchange among various

functional group for which non-changeover type contacts ('NC' or

'NO') shall be wired to the control system. The binary inputs

required for information purposes only shall be wired to control

system in the form of non-changeover type contacts.

b) The conditioning and processing functions to be performed as a

minimum for the binary inputs coming for control and information

purposes shall be:

1. 24V/ 48 V DC power supply for contact interrogation for all

potential free contacts with per point fuse protection or suitable

current limit feature/ isolation through opto-coupler.

2. Contact bounce filtering delay time of 15 milliseconds.

3. Facility for pegging the binary signal to logic one/zero or last

correct value in case of failure of binary input module.

4. Binary signal distribution to different users shall be in such a

way so as to ensure that a short/ground fault on one user is not

reflected to the other user.

5. Implementation of multiple measurement schemes for signals

for control purpose.

6. All binary signals shall be acquired, validated, processed, alarm

checked and their data base updated within one second. In

addition to this requirement, binary signals required for SOE

shall have a resolution of 1millisecond.

1 2 ... 149 150 151 152 153 154 155 156 157 158 159 ... 221 222

No comments

Crown Boiler MWC Series Specifications Page 154