Endress+Hauser Liquipoint FTW 31 - Compact Instrumentation Details; FEW 54 Relay Output Implementation

Liquipoint T FTW 31, FTW 32
10 Endress + Hauser
Compact instrumentation with FEW 54
Relay contact circuit for load
The connected load is switched via potential-free relay contacts (change-over contact).
In the event of a level alarm or a power failure, the relay contacts break the connections between
terminals 3 and 4 and terminals 6 and 7. The relays always switch simultaneously.
Protection against voltage peaks and short-circuits
When connecting a device with high inductance, fit a spark barrier to protect the relay contact.
A fine-wire fuse (load-dependent) can protect the relay contact in the event of a short-circuit.
L00-FTW3xxxx-04-05-xx-en-002
Connecting the FEW 54 electronic insert.
– F
1
: Fine-wire fuse 500 mA, semi-time lag
– F
2
: Fine-wire fuse to protect the relay contact, load-dependent
– M: Ground connection to protective earth (PE)
Power supply (FEW 54)
• Supply voltage: U% 20 V…55 V DC or U& 20 V…253 V AC, 50/60 Hz
• Peak inrush current: max. 2 A, max. 400 µs
• Output: two potential-free change-over contacts
• Contact load capacity: U~ max. 253 V, I~ max. 4 A, U% 30 V/4 A; 150 V/ 0.2 A
Power consumption
• P < 2,0 W
Current consumption
• 60 mA
ru– a+rua
FEW 54
L1 N
F
1
F
2
F
2
12 4 78365
M
PE
Mains
Potential-free change-over contacts
PE
Vessel