Honeywell 700 User Manual

33

66-2069—02

Models: 700ACSP & 700DCSP

The safety function of the 700 signal processor consists of a 

Flame Relay which comprises its safety function and behaves 

as follows:

The Flame Relay (Normally Open)

• The Flame Relay will be 

energized when the signal 

processor is powered and a flame on condition is detected.

• The Flame Relay will be 

de-energized when the signal 

processor is powered, a flame of condition is detected, and 

the FFRT (Flame Failure Response Time) has elapsed.

• The Flame Relay will be 

de-energized when the signal 

processor is powered and detects a fault condition.

• The Flame Relay will be 

de-energized when power to the 

signal processor is off.

λ

λ

λ

700AC

3

0

>99%

1.79 x 10

-4

1.93 x 10

-6

8.53 x 10

-9

8.20 x 10

-9

700DC

3

0

>99%

1.79 x 10

-4

1.36 x 10

-6

8.53 x 10

-9

8.20 x 10

-9

System Architecture

1oo1

MTTR (Mean Time to Restoration

8 hours

Proof Test Interval

5 years

Fit for use in 

SIL 3 environment

Dangerous Failure

Failure which has the potential to put the safety-related system in a hazardous or fail-to-function 

state.

Safety-related System

A system that implements the required safety functions required to achieve or maintain a safe 

state and is intended to achieve on its own or with other systems the necessary safety integrity for 

the required safety functions.

Safety Function

Defined function, which is performed by a safety-related system with the aim of achieving or 

maintaining a safe state for the plant, in respect of a specified hazardous event.

Proof Test

Periodic test performed to detect failures in a safety-related system so that, if necessary, the 

system can be restored to an “as new” condition or as close as practical to this condition.

MTTR (Mean Time to 

Restoration)

The average duration required for restoration of operations after a failure.

λ

sd

Rate of safe detectable failures per one billion hours.

For example if 

λ

sd 

= 3000, then it is estimated that there will be about 3,000 safe detectable 

failures during every one billion hours of operation.

For 

λ

sd 

= 3000, this is about one safe detectable failure every 38 years.

λ

su

Rate of safe undetectable failures per one billion hours.

λ

dd

Rate of dangerous detectable failures per one billion hours.

λ

du

Rate of dangerous undetectable failures per one billion hours.

HFT

Hardware Fault Tolerance

System Architecture

Specific configuration of hardware and software elements in a system.

PFD

AVG

 (Average Probability 

of Failure on Demand)

Average Probability of Failure on Demand. In this case, regarding the 700 Signal Processor.

FIT (Failures in Time)

A unit of measurement representing one failure per billion hours. 1,000,000,000 hours is 

approximately 114,155.25 years.