Honeywell-System 57 5704 Control System

Honeywell-System 57 5704 Control System

2. Construction The system consists of individual 1'' (63.5px) wide cards fitted to a rigid custom rack designed to fit Euro rack cabinets. Two rack widths are available: a. 19 inch with 17 card slots to house up to 16 Four Channel Control  Cards and an Engineering Card. b. Half 19 inch with nine card slots to house up to eight Four Channel  Control Cards and an Engineering Card. Each sub-rack contains an Engineering Card and a DC Input Card to  make up the rack system The system is designed to meet the differing customer wiring  configurations and to achieve this the control functions are split away from the relays and field wiring connections. Four channels of gas detection therefore consists of: a. Four Channel Control Card Each Four Channel Control Card functions independently and  contains all the necessary electronic circuitry to provide the sensor  drive, alarm detection and gas level display for four channels of gas  detection. There are two types of Four Channel Control Cards, one for catalytic  inputs and the other for 4 - 20mA inputs. b. Quad Relay Interface Card The Quad Relay Interface Card provides the interface connections  between the Control Card and the respective field connected gas sensors. In addition, it provides four alarm outputs via the field connections. c. Relay Interface Assembly Where additional relay contacts are required, an Expansion Relay  Card is attached to the Quad Relay Interface Card. The new  assembly becomes the Relay Interface Assembly and expands the  alarm relays to 16. This combination occupies two interface card  slots and as a consequence limits the number of control cards that  can be fitted to the rack.

In a system where the field wiring is required to be connected to the rear of the system, the rack is centrally divided into front and rear sections  by a printed circuit board backplane which provides common signal  routeing between individual Four Channel Control Cards. The control  cards are fitted at the front of the rack while Quad Relay Interface Cards are fitted directly behind the associated Four Channel Control Card at the rear of the rack. The control cards and their respective interface  cards are interconnected by a plug and socket arrangement. In a system where the field wiring is required to be connected to the front of a system, the Four Channel Control Cards and Quad Relay Interface  Cards are mounted one above the other in a 6U rack. The backplane  printed circuit board still provides the common signal routeing between  the individual Four Channel Control Cards, but short cables at the rear  of the cards connect each control card to their respective Quad Relay  Interface Card. Simple calibration and checking of the system is carried out using push  buttons on the Engineering Card fitted in each rack. More complex configuration can be carried out using the RS232 link between the Engineering Card and an external IBM compatible personal computer  running the engineering interface software. When a Relay Interface Assembly is used, the resultant four channel  control assembly then takes up two card slots. A mixture of 5704 and 5701 Control Cards may be fitted in the same System 57 rack. The 5704 Control System is shown in Figure 1.

2. Racks

Each rack assembly contains a sub-rack, Engineering Card, DC Input

Card, key kit and where necessary an interconnecting cable.

Dependent upon configuration, the control system is housed in one of

four standard size sub-racks as follows:

a. Full 19 inch wide by 3U high - Part Number 05701-A-0511.

for rear field wiring connections.

b. Full 19 inch wide by 6U high - Part Number 05701-A-0501.

for front field wiring connections.

c. Half 19 inch wide by 3U high - Part Number 05701-A-0512.

for rear field wiring connections.

d. Half 19 inch wide by 6U high - Part Number 05701-A-0502.

for front field wiring connections.

All four versions have two separate chambers. One is sealed against

electromagnetic interference and contains the control cards while the

other chamber contains the relay interface cards. A backplane between

the two chambers provides a path for signal routeing between individual

control cards and the Engineering Card.

4.2 Control Functions

The Four Channel Control Card carries out the control functions for up

to four loops of gas detection as follows:

a. Provides the necessary voltages and currents to drive the connected

sensors.

b. Processes the incoming sensor signals.

c. Displays the signal levels, one at a time, on the front panel liquid

crystal display.

d. Compares each channel signal level with pre-defined alarm limits.

e. When the pre-defined alarm limits are exceeded, raises the alarms

by lighting up front panel LEDs and operating connected relays.

f. Informs other cards with the alarm status information.

g. Self validates the operation of its circuit components, software

operation and the condition of the sensor.

4.3 Analogue Output Module

Optional Analogue Output Modules may be factory fitted to the Four

Channel Control Card and are used on each channel of gas detection

to provide a current loop output which follows the sensor signal level.

This may be set electronically to produce a 0 - 20mA output or a 4 -

20mA output and can be used to operate a chart recorder, data logger,

PLC, etc. Two versions are available:

a. Analogue Output Module, Current Sink

Part Number 04200-A-0145

b. Analogue Output Module, Current Source

Part Number 04200-A-0146