Flowserve NRS 1-50 For TWO Electrodes - Manual (Page 13)

3
Electrical Connection
Connection of level electrode
To connect the level electrode(s) use screened multi-core control cable with a min. conductor size
0.5 mm , e.g. LiYCY 4 x 0.5 mm .
Max. length 00 m with an electrical conductivity of the boiler water > 0 μS/cm at 5 °C.
Max. length 30 m with an electrical conductivity of the boiler water < 0 μS/cm at 5 °C.
Wire terminal strip in accordance with the wiring diagram.
Fig. 5.
Connect screens only to terminals 5 and 3.
Connect the safety circuit for the heating to terminals 3, 4 and 6, 7. Wenn used as water level
limiter according to TRD, EN 95 / EN 953 connect the output contacts of the two monitoring
channels by adding a wire link between the terminals 4 and 6.
Provide the output contacts with a A or A (for 7 hours operation acc. to TRD 604) slow-blow fuse.
Connection of safety circuit
Installation
Mounting level switch NRS 1-50
The level switch NRS -50 is clipped onto the support rail 7 type TH 35, EN 6075 in the control
cabinet. Fig. 6
For connecting the level switch with the logic unit use a control cable, e. g. x 0.5 mm .
The control voltage must not exceed 36 V DC.
Connection of logic unit (standby input)
Note
n
In the event of an alarm the level switch NRS -50 does not interlock automatically.
If a lock function is required by the installation it must be provided in the follow-up
circuitry (safety circuit). The circuitry must meet the requirements of the EN 5056.
A signal output for the connection of further external signalling equipment is allocated to each
monitoring channel in the level switch, max. load 00 mA. For connecting the level switch with the
logic unit use a control cable, x 0.5 mm . In the event of an alarm or error message the signal
outputs (terminals 0, and 9, 30) open instantaneously.
Connection for signal output
Mains supply
Provide the level switch NRS -50 with an external semi-delay fuse 0.5 A.