RAILWAY SYSTEMS & SOFTWARES


RS4 – SIL4 202 Safety Relay


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Safety systems control is often done via safety relays. There is often confusion in the terms used for the notion of safety relay:

TECHNICAL FEATURES


It integrates two PCB relays which meet NF F50205 standard (forcibly guided relay).
> The two PCB relays are coming from different series to protect against the shared modes introduced by manufacturing errors involving a single series.
> Two “working” contacts from each PCB relay are twisted in series to work out the security output.
> The distances between the internal tracks and the pins of the safety control must respect the NF F74003 standard to guarantee the absence of a short circuit
> The distances between the control of the PCB relays and the security output strips must resist to insulation tensions of 2000Vac.
> The circuit safety is processed with a SIL4 safety level
> RS4 relay is “fail safe”, including design based on component failure according to EN50129 standard

Documents and ISA* Certification


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>  CERTIFER CERTIFICATE NUMÉRO ECI_8349 – EN50129
Download datasheet

 

*Independent Safety Assessor

Relays guaranteed to be fail-safe and “forcibly guided”


> In reality a lot of safety relays are simply forcibly guided relays according to EN 50205 standard, guaranteeing that it is impossible that a NO (Normally Opened) contact and a NC (normally closed) contact are established at the same time.

> Relays like the NS1 relays which meet NF F 70 030 standard, are also guaranteed to be fail-safe (not all the NS1 relays, and the RU are not). The fail-safe guarantee is obtained by the fact that the moving part of the relay is orientated in relation to earth’s attraction. This way, via the effect of gravity”, the “working” contacts open if the relays coil is not powered.

> This implies that these relays may not be used in-board. These relays are mainly used in rail signalling facilities and are considered to be intrinsic safety relays with a SIL4 safety level.

> The standard emphasize on the fact that these safety characteristics are only valid if the terms of use for these relays are respected (maximum supply tension at 28.8V, maximum current in the limited contacts, etc…).

Why has CLEARSY developed the RS4 relays ?


> We have developed and set up systems like COPPILOT, COPP, DOF1 and DIL which are intended to control the platform screen doors of various underground rail systems. The opening function on these systems is level SIL3. The opening control is achieved through existing relay contact in working position. The security of the safety function on CLEARSY’s systems is based on the fact that we safely detect that the relay has remained “stuck” in the condition in which working contact is established.

This principle was used to produce the RS2 relay: this relay is made up of 2 forcibly guided relays and allows, thanks to an external check of the contacts (by a security automaton for example) to guarantee a SIL3 safety level.

> For security applications which have no checking system, we have designed an automatically checked relay named RS4. The RS4 is functionally comparable to the NS1 because the RS4 relay is an intrinsic safety relay with a SIL4 safety level. The RS4 is “forcibly guided ” AND ” fail-safe “, including design based on component failure according to EN50129 standard. Like the NS1 relay, certain conditions of use are respected to guarantee the SIL4 safety integrity.

THIS RELAY MEETS THE NEEDS THIS BELOW:

> It integrates two PCB relays which meet NF F 50205 standard (forcibly guided relay).
> The two PCB relays are coming from different series to protect against the shared modes introduced by manufacturing errors involving a single series.
> Two “working” contacts from each PCB relay are twisted in series to work out the security output.
> The distances between the internal tracks and the pins of the safety control must respect the NF F 74003 standard to guarantee the absence of a short circuit.
> The distances between the control of the PCB relays and the security output strips must resist to insulation tensions of 750V.
> The circuit safety is processed with a SIL4 safety level
> RS4 relay is “fail safe”, including design based on component failure according to EN50129 standard

Mecanic and connectics


TERMINAL ASSIGNMENT :

> LB+ B- : Ligne command (input between 18 and 45 Ω)
> PB+ B- : Poste command (input < 18 Ω)
> OA1 OA2 : NO A Contact
OB1 OB2 : NO B Contact
CA1 CA2 : NF A Contact (type 2)
CB1 CB2 : NF B Contact (type 1)

Only one input can be use at the same time (LB+ or PB+).
NO means a normally open contact (or working contact).
NC means a normally closed contact (or break contact).

Caracteristics


1.1 Nominal voltage (VDC) : 24, 48, 72, 110 (other on demand)
1.2 Nominal power (W) : 1,7 (model 24Vdc)
1.3 Operating voltage range (V) :22,56 … 28,8 Vdc (model 24 Vdc)
1.4 Drop out specified (Un) : More than 0,1*Un, mean > 2 Vdc
1.5 Command signal maximum rise time (ms) :The command signal must rise from 0 to the nominal
1.6 Relay minimum command current (A) : at least 0.8A
1.7 Maximum number of switching per second should not be exceeded (Switching/secondes) : 1
1.8 Power input maximum equivalent series resistance (this value should be used to calculate the maximum conductor length in fuction of the wire type Ω/meter value)  : ≤ 18Ω on “poste” input, 18Ω<R≤45Ω on “line” input

2.1 Contacts configuration : 2NO / 2NF forcibly guided contacts in accordance with EN50205 standard
2.2 Contact material : AgNi 0,15 + 5um Au
2.3 Dielectic strength between coils and contacts and between contacts, maximum conact breaking nominal voltage, minimum contact making voltage : (VAC, V, V) : 2000 (1 minute), 1 VAC et 1 VDC, 230 VAC et 230 VDC
2.4 Minimum making current (mA) : 4
2.5 Maximum nominal load current : 3A DC/AC
2.6 Minimum power making (mW) : 4
2.7 Maximum AC power breaking (VA) : 460VA in VAC
2.8 Electrical life expectancy, 230Vac 3A cos ф = 1, 24Vdc 3A, Sous 230VAC 0.3A cos ф = 1, Sous 24VDC 0.3A2 (Switching) : Greater than 2.2*10^5, Greater than à 1.5*10^5, Greater than à 3*10^6, Greater than à 1*10^6.
2.9 Pick-up closure time contact Ta for NO contacts: 5<Ta<120 ms, Typical at 24 VDC : 35ms
2.10 Drop-out opening contact time T’c for NO contacts (ms) : 5<T’c<50ms, Typical at 24 VDC : 28ms
2.11 Pick-up closure time contact Ta for NC contacts (ms) : 1<ta<60 ms, Typical at 24 VDC NF1:20 ms, Typical at 24 VDC NF2: 4 ms
2.12 Drop-out opening contact time tc for NC contacts (ms) : 1<tc<40 ms, Typique sous 24 VDC NF1: 7 ms, Typique sous 24 VDC NF2: 7ms
2.13 Contact bouncing (ms) : 20

3.1 Mechanical like : Greater than 20*10^6
3.2 MTTR (hour) : 0,08
3.3 Operating temperature range (°C) : -25 … +70 (T1 Class EN 50155)
3.4 Choc and vibration : Compliant EN61373 category 1 classe B
3.5 Supply interruption : S1 according to EN 50155 (no interruption)
3.6 Supply change over : C1 according to EN 50155 (0,6 Un during 100ms)