Special Conditions For Safe Use (Iecex And Atex); Functional Safety - Db1H; Assessment Of Functional Safety - Eaton MEDC DB1 Technisches Handbuch

Technical Manual for the Sounders – DB1 & DB1H
English
6.0 SPECIAL CONDITIONS FOR SAFE USE
(IECEx and ATEX)
1. The enclosure is a potential electrostatic charging
hazard, and should only be cleaned with a damp cloth.

7.0 FUNCTIONAL SAFETY - DB1H

Introduction
The DB1H Sounder has been designed for use in poten-
tially explosive atmospheres and harsh environmental
conditions. The marine grade alloy or stainless enclosures
are for use offshore or onshore, where light weight
combined with corrosion resistance and strength is
required.
The safety function of the Sounder is to provide a pre-
determined audible warning sound when required if the
correct voltage is applied to the unit. The DC version of
the Sounder is designed to operate on a supply voltage
tolerance of +/- 20%,
Under No fault (Normal) Operating conditions the DB1
Sounder will provide an audible warning sound when
required by the system.
DB1H SOUNDER
Table 3.
Safety Function of DB1H Sounder: To provide a pre-described audible warning sound when required
Summary of Clauses
2/7.4.2 and 2/7.4.4
Architectural constraints
Safe Failure Fraction (SFF)
Random hardware failures: [h ]
-1
Random hardware failures: [h ]
-1
PFD @ PTI = 8760Hrs
MTTR = 8 Hrs
Average freq. of dangerous failure
(high demand-PFH) [h ]
-1
Hardware safety integrity compliance
Systematic safety integrity compliance
Systematic Capability
(SC1, SC2, SC3, SC4)
Hardware safety integrity achieved
4
TECHNICAL MANUAL FOR THE SOUNDERS – DB1 & DB1H TM153 Issue I August 2019 www.eaton.com
DB1H Sounder
Single Mode (1oo1)
HFT=0
65%
DD
DU
SD
SU
3.89E-04
8.86E-08
Route 1
H
Route 1
s
SC2
Limited to: SIL 1 (1oo1) & SIL 2 (1oo2) due to SFF value.
Under fault conditions the failure mode of the Sounder
is a failure to provide an audible warning sound. For the
failure rate associated with this failure mode please refer
to the table below.
New electronic circuitry allows the DB1 and DB1H to be
switched between two user selectable tones by either
reversing the polarity, or connecting a second voltage
supply (dual tone facility is available on dc units only).
The higher output DB1H is particularly suitable for noisy
environments.

Assessment of Functional Safety

This Sounder is intended for use in a safety system
conforming to the requirements of IEC61508. UL has
conducted a Failure Modes Effect and Diagnostic Analysis
(FMEDA) of the DC version of DB1H Sounder against
the requirements of IEC 61508-2 using a Proof Test
Interval of 8760hrs.
The results are shown below and are based on Route 1
The Sounder is classed as a Type B device
DB1H Sounder
Redundant Mode (1oo2)
HFT=1
65%
6.45E+09
8.87E-08
0.00E+00
1.59E-07
3.89E-05
8.86E-09
h
Verdict
Type B
SIL 1(1oo1)
SIL 2 (1oo2)
6.45E+10
8.87E-09
0.00E+00
1.59E-08
SIL 3(1oo1)
SIL 3(1oo1)