Flowserve NRS 1-50 For TWO Electrodes - Manual (Page 17)

7
Electrical Connection
– continued –
Explanatory notes to schematic respresentations
Steam boiler plants according to TRD 604, EN 12952-07 / EN 12953-06, 72 h operation
Fig. 8
Combination consisting of level electrodes NRG ...-50 and level switch NRS -50 as water level
limiter. Functional safety IEC 6508, SIL 3.
The equipment combination meets the demand for two independent water level limiters.
(Pressurized) hot-water plants and electrically heated steam boilers according to TRD 604,
EN 12953-06
Steam boiler plants with high availability according to TRD 604, EN 12952-07 / EN 12953-06,
72h operation
Fig. 9
Combination consisting of level electrode NRG ...-50 and level switch NRS -50 as water level
limiter. Functional safety IEC 6508, SIL 3.
Hot water installations require two independent and separate water level limiters. For this purpose
one equipment combination NRG ...-50/NRS -50 shall be installed in the hot-water boiler and the
second one in the pressure maintaining vessel, the expansion tank or the like (depending on the type
of pressurization). For electrically heated steam boilers one water level limiter is sufficient.
To meet the plant operator's demand for a higher level of availability of the steam boiler plant, two
(or three) independent equipment combinations NRG ...-50/NRS -50 can be installed in the steam
boiler.
Further applications in accordance with national sets of regulations
Fig. 10
Combination consisting of level electrode NRG ...-50 and level switch NRS -50 as
water level limiter.
The level switch opens two separate safety circuits. Functional safety IEC 6508, SIL 3.
Fig. 11
Combination consisting of level electrodes NRG ...-50 and level switch NRS -50 as
water level limiter.
The level switch opens two separate safety circuits. Functional safety IEC 6508, SIL 3.
Fig. 12
Combination consisting of level electrode NRG ...-50 and level switch NRS -50 as
water level limiter and level electrode NRG ...-50 / level switch NRS -50 as first low-level alarm.
Functional safety IEC 6508, SIL 3.
Fig. 13
Combination consisting of level electrodes NRG ...-50 and level switches NRS -50 as
water level limiter.
The level switch opens two separate safety circuits. Functional safety IEC 6508, SIL 3.
Note
n
Please observe the safety-related characteristics for the equipment combination level
electrode NRG ...-50 / NRG 6-36 / level switch NRS -50 and level electrodes
NRG ...-50 / level switch NRS -50 on page 6, Fig. 1.