Flowserve NRS 1-7 - Manual (Page 14)

14
Wiring
NRS 1-7
Cable required for wiring to the electrode: four-core screened cable, e. g. I-Y(St)Y 2 x 2 x 0.8 or
LIYCY 4 x 0.5².
Max. cable length 100 m with a conductivity from 10 µS/cm.
Max. cable length 30 m with a conductivity from 0.5 µS/cm.
Max. cable length 15 m with a conductivity from 0.5 µS/cm when used in conjunction with inverter
URN 1 (24 V d. c.)
Tools
■ Screwdriver for slotted screws, size 2.5, completely insulated according to VDE 0680-1.
Voltage table
Use this voltage table as reference when checking the level electrode for malfunction or submersion.
Take the wiring diagram (see Fig. 10, Fig. 11) into account.
U
1-2
10 V
eff
0.5 µS/cm,
C = 0.13 cm -1
2 V
eff
10 µS/cm,
C = 0.3 cm -1
U
1-
⊥ ⊥⊥ ⊥⊥
U
2-
⊥ ⊥⊥ ⊥⊥
Submerged Exposed Malfunction (submerged/alarm)
U
1-2
2
<
U
1-2
2
≥
U
1-
⊥ ⊥⊥ ⊥⊥
≤
Attention
■ To protect the switching contacts provide the circuit with a 2.5 A slow-blow fuse or
according to TRD regulations (1.0 A for 72 hrs operation).
■ The screen must not make any other electrical contact.
Note
■ The self-checking routine of the amplifier NRS 1-7 reduces U
1-2
every 40 sec.
considerably, even down to 0 volt.
■ Connect screen only to terminal 8 of the temperature switch.
■ The sensitivity is indicated on the name plate.
■ The rated voltage is indicated on the name plate.
■ When switching off inductive loads, voltage spikes are produced that may impair the
operation of control and measuring systems. Inductive loads should therefore be
provided with commercial arc suppressor RC combinations, e. g. 0.1 µF / 100
Ω.