Endress+Hauser FTL51C Specifications

TI00347F/00/EN/14.18
71412981

Products Solutions Services

Technical Information

LiquiphantM
FTL51C

Vibronic

Point level switch for all kinds of liquids
with high corrosion-resistant coating

Application

The Liquiphant M is a point level switch for use in all liquids
– for temperatures of –50 °C to 150 °C (-58 to 302 °F)
– for pressure up to 40 bar (580 psi)
– for viscosities up to 10000 mm
– for densities of 0.5 g/cm (SGU) or 0.7 g/cm(SGU)

The device functions reliably regardless of flow, turbulence, bubbles, foam, vibration,
solids content or buildup, making the Liquiphant an ideal substitute for float switches.

All the wetted parts of the sensor (process connection, extension pipe and tuning fork)
are coated in enamel or various synthetic materials, making the point level switch
suitable for applications in very aggressive liquids.

International approvals certify use in hazardous areas.

Your benefits

• Use in safety systems requiring functional safety to SIL2/SIL3 in accordance with
IEC 61508/IEC 61511-1

• Optimally adapted to the process with a wide range of materials for corrosion­resistant coating

• Large number of process connections to choose from
– Flanges for various standards
– Universal usage

• No adjustment: quick, low-cost startup

• No mechanically moving parts: no maintenance, no wear, long operating life

• FDA-approved material (PFA Edlon)



/s (cSt)

Table of contents

Liquiphant M FTL51C

Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Point level detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Function and system design . . . . . . . . . . . . . . . . . . . . . .4

Measuring principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Modularity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Electronic versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Electronic version for density measurement . . . . . . . . . . . . . . . 5

Galvanic isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Measured variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Measuring range (detection range) . . . . . . . . . . . . . . . . . . . . . . 5

Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Electronic insert FEL51 (AC 2-wire) . . . . . . . . . . . . . . .6

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Connectable load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Electronic insert FEL52 (DC PNP). . . . . . . . . . . . . . . . . .8

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Connectable load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Electronic insert FEL54 (AC/DC with relay output). . .9

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Connectable load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Electronic insert FEL55 (8/16 mA) . . . . . . . . . . . . . . 10

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Connectable load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Connectable load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Electronic insert FEL57 (PFM) . . . . . . . . . . . . . . . . . . 13

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Connectable load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Electronic insert FEL50A (PROFIBUS PA) . . . . . . . . . 14

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Electronic insert FEL50D (density). . . . . . . . . . . . . . . 16

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Operating principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Light signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Connection and function . . . . . . . . . . . . . . . . . . . . . . . 18

Connecting cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Safety mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Switching time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Switch-on behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Performance characteristics . . . . . . . . . . . . . . . . . . . . 18

Reference operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . 18

Maximum measured error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Influence of medium temperature . . . . . . . . . . . . . . . . . . . . . . . 18

Influence of medium density . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Influence of medium pressure . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Switching delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Installation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Examples of mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Electronic insert FEL56 (NAMUR L-H edge). . . . . . . 11

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Connectable load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Electronic insert FEL58 (NAMUR H-L edge). . . . . . . 12

Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Signal on alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Ambient temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Storage temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Operating altitude as per IEC61010-1 Ed.3 . . . . . . . . . . . . . . . 22

Climate class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Degree of protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Vibration resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Electromagnetic compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Medium conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Medium temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Thermal shock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2 Endress+Hauser

Medium pressure pe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Test pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Pressure shock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

State of aggregation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Solids content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Lateral loading capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Mechanical construction . . . . . . . . . . . . . . . . . . . . . . . 24

Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Weights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Process connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Human interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Electronic inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Operating concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Certificates and approvals . . . . . . . . . . . . . . . . . . . . . . 30

Certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

CE mark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

RoHS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

RCM-tick mark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

EAC conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

CRN approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Pressure Equipment Directive 2014/68/EU (PED) . . . . . . . . . 31

Process seal according to ANSI/ISA 12.27.01 . . . . . . . . . . . . . 31

Other certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Manufacturer declarations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Use in hazardous zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Liquiphant M FTL51C

Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Transparent cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Cover with sight glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Weather protection cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Technical Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Functional safety (SIL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Safety Instructions (ATEX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Safety Instructions (NEPSI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Control Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3 Endress+Hauser

Liquiphant M FTL51C

FEL51/52/54

…

FEL55/56/57/58/50A

Ex i

-

.

1

Application

Point level detection Maximum or minimum detection in tanks or pipes containing all kinds of liquids, including use in

hazardous areas. Particularly suitable for very aggressive liquids thanks to high level of corrosion
protection.

Function and system design

Measuring principle The sensor's fork vibrates at its intrinsic frequency.

This frequency is reduced when covered with liquid. This change in frequency causes the point level
switch to switch.

Modularity

Point level switch

Liquiphant M FTL with electronic versions
FEL51, FEL52, FEL54

Point level switch

Liquiphant M FTL with electronic versions
FEL55, FEL56, FEL57, FEL58
for connecting to a separate switching unit
or an isolating amplifier FEL50A
for connecting to a PROFIBUS PA segment

4 Endress+Hauser

1 = Switching unit, PLC, isolating amplifier, segment coupler

Liquiphant M FTL51C

Electronic versions FEL51:

Two-wire AC version;
Switches the load directly into the power supply circuit via an electronic switch.

FEL52:
Three-wire DC version;
Switches the load via the transistor (PNP) and separate connection e.g. in conjunction with
programmable logic controllers (PLCs), DI modules as per EN 61131-2.

FEL54:
Universal current version with relay output;
Switches the loads via 2 floating change-over contacts.

FEL55:
Signal transmission 16/8 mA on two-wire cabling e.g. in conjunction with programmable logic
controllers (PLCs), AI modules 4 to 20 mA as per EN 61131-2.

FEL56:
For separate switching unit; signal transmission L-H edge 0.6 to 1.0 / 2.2 to 2.8 mA
to EN 50227 (NAMUR) on two-wire cabling.

FEL58:
For separate switching unit; signal transmission H-L edge 2.2 to 3.5 / 0.6 to 1.0 mA
to EN 50227 (NAMUR) on two-wire cabling.
Connection cabling and slave devices tested by pressing a key on the electronic insert.

FEL57:
For separate switching unit; PFM signal transmission;
Current pulses superimposed on the power supply along the two-wire cabling.
Proof testing from the switching unit without changing levels.

FEL50A:
For connecting to PROFIBUS PA;
Cyclic and acyclic data exchange acc. to PROFIBUS-PA Profile 3.0; Discrete Input.

Electronic version for density measurement

Galvanic isolation FEL51, FEL52, FEL50A: between sensor and power supply

Design FTL51C: flange, extension pipe and tuning fork are coated.

FEL50D:
For connecting to Density Computer FML621

FEL54: between sensor and power supply and load

FEL55, FEL56, FEL57, FEL58, FEL50D: see connected switching unit

Input

Measured variable Level (limit value)

Measuring range (detection range)

Density Setting on the electronic insert > 0.5 g/cm

Depends on the mounting point or the length of the sensor with extension pipe.
Up to 3000 mm (118 in) for synthetic coating, up to 1200 mm (47.2 in) for enamel coating



or > 0.7 g/cm (other on request)

Endress+Hauser 5

Electronic insert FEL51 (AC 2-wire)

L1
U~ 253 V AC≤

50/60 Hz

1A

min.

19 V

FEL51

!

1 2

1

R

N

PE

N

1

MAX

MIN

Power supply Supply voltage: AC 19 to 253 V

Power consumption: < 0.83 W
Residual current consumption: < 3.8 mA
Short-circuit protection
Overvoltage protection FEL51: overvoltage category III

Electrical connection Two-wire AC connection

Switches the load directly into the power supply circuit via an
electronic switch.

Always connect in series with a load!

Check the following:

• The residual current in blocked state
(up to 3.8 mA)

• That for low voltage
– the voltage drop across the load is such that the

minimum terminal voltage at the electronic insert
(19 V) when blocked is not undershot.

– the voltage drop across the electronics when switched

through is observed (up to 12 V)

• That a relay cannot de-energize with holding power
below 3.8 mA.
If this is the case, a resistor should be connected parallel to
the relay. An RC module is available under the part
number: 71107226.

• When selecting the relay, pay attention to the holding
power / rated power
(see "Connectable load")

Liquiphant M FTL51C

1 = External load must be connected.

Output signal

I

L

= load current

Safety mode Level Output signal LEDs

(switched through)

< 3.8 mA

= residual current

(blocked)

= lit

= unlit

L00-FTL2xxxx-07-05-

xx-xx-000

Signal on alarm Output signal on power failure or in the event of damaged sensor: < 3.8 mA

Connectable load • Voltage drop via FEL51

• Residual current if electrical switch is blocked:

12 V

 3.8 mA

• Load switched directly into the power supply circuit via the thyristor.
Transient (40 ms)

The load is switched via an electronic switch directly in the power circuit.
Always connect in series with a load!
Not suitable for connection to low-voltage PLC inputs!

 1.5 A,  375 VA at 253 V or  36 VA at 24 V (not short-circuit-proof)

green red

6 Endress+Hauser

Liquiphant M FTL51C

2.7

2.5

2.3

2.1

1.9

1.7

1.5

1.3

1.1

0.9

0.7

0.5
20 24 27 43 48 53 60 110 121 207 230 253

P/S

U

P1

Selection guide for relays

Minimum nominal power of load
P/S nominal power in [W] / [VA]
U operating voltage in [V]

Position Operating voltage Nominal power

min. max.

P1
AC operation

24 V
110 V
230 V

> 1.3 VA
> 1.5 VA
> 2.5 VA

< 8.4 VA
< 38.5 VA
< 80.5 VA

Relays with less nominal power can be operated via an RC module connected in parallel (optional).

Endress+Hauser 7

Electronic insert FEL52 (DC PNP)

1 2 3

(+)

FEL52

L+

L–

–

0.5 A

U– 10…55 V DC

...

PE

R

MAX

MIN

L+ +

1 3

L+ +

1 3

1 3

1 3

I

L

I

L

< 100 μA

< 100 μA

Power supply Supply voltage: DC 10 to 55 V

 1.7 V, 0 to 400 Hz

Ripple:
Current consumption:  15 mA
Power consumption:  0.83 W
Reverse polarity protection
Overvoltage protection FEL52: overvoltage category III

Electrical connection Three-wire DC connection

Switches the load via the transistor (PNP) and separate
connection.
Preferably used with programmable logic controllers (PLC),
DI modules as per EN 61131-2.
Positive signal at the switch output of the electronics (PNP);
output blocked when point level is reached.

Liquiphant M FTL51C

Output signal

I

L

= load current

Safety mode Level Output signal LEDs

(switched through)

< 100 μA

= residual current

(blocked)

= lit

= unlit

L00-FTL2xxxx-07-05-

xx-xx-000

Signal on alarm Output signal on power failure or in the event of damaged sensor: < 100 μA

Connectable load • Load switched via the transistor and separate PNP connection,

•Load current

 350 mA (pulsed overload and short-circuit protection)

• Residual current < 100 μA (with transistor blocked)

• Capacitance load

• Residual voltage < 3 V (with transistor switched through)

 0.5 μF at 55 V,  1.0 μF at 24 V

R = Relay, PLC, ...

green red

 DC 55 V

8 Endress+Hauser

Liquiphant M FTL51C

L1
L+

a

NO

a

NO

u

C

u

C

N

L–

r

NC

r

NC

0.5 A

PE

1 2 6 7 83 4 5

FEL54

U~ 19…253 V AC, 50/60 Hz
U– 19… 55 V DC

...

1

22

MAX

MIN

354

354

687

687

354

354

687

687

Electronic insert FEL54 (AC/DC with relay output)

Power supply Supply voltage: AC 19 to 253 V, 50/60 Hz or DC 19 to 55 V

Power consumption:
Reverse polarity protection
Overvoltage protection FEL54: overvoltage category III

Electrical connection Universal current connection with relay output

Power supply:
Please note the different voltage ranges for
AC and DC.

Output:
When connecting an instrument with
high inductance, provide a spark arrester
to protect the relay contact.
A fine-wire fuse (depending on the
load connected) protects the relay
on short-circuiting.
Both relay contacts switch simultaneously.

 1.3 W

Output signal

Signal on alarm Output signal on power failure or in the event of damaged sensor: relay de-energized

Connectable load • Loads switched via 2 floating change-over contacts (DPDT)

Endress+Hauser 9

1 = When jumpered, the relay output works with NPN logic.
2 = See below: "Connectable load"

Safety mode Level Output signal LEDs

green red

= relay energized

= relay de-energized

= lit

= unlit

L00-FTL2xxxx-07-05-

xx-xx-001

 6 A (Ex de 4 A), U~  AC 253 V; P~  1500 VA, cos  = 1, P~  750 VA, cos  > 0.7

•I~

•I%

 6 A (Ex de 4 A) to DC 30 V , I%  0.2 A to 125 V

• When connecting a low-voltage circuit with double insulation according to IEC 1010, the following
applies: the sum of the voltages of the relay output and power supply is

 300 V

• The electronic insert FEL52 DC-PNP is preferred for low DC load currents (e.g. when connecting to
a PLC)

• Relay contact material: silver/nickel AgNi 90/10

Electronic insert FEL55 (8/16 mA)

1 2

FEL55

–

Ex ia

+

U 11...36 V DC

–

+

–

+

R

R =

max

U – 11 V

16.8 mA

1

2

-

.

MIN

+
2 1

+
2 1

+
2 1

+
2 1

~16 mA

~8 mA

~8 mA

~16 mA

MAX

Power supply Supply voltage: DC 11 to 36 V

Power consumption: < 600 mW
Reverse polarity protection
Overvoltage protection FEL55: overvoltage category III

Electrical connection Two-wire connection for separate switching unit

For separate switching unit.
Signal transmission 16/8 mA on two-wire cabling.
For connection to programmable logic controllers
(PLC) for example, AI modules 4 to 20 mA to
EN 61131-2.
Output signal jump from high to low current on
point level.

Fuse required for non-Ex applications!
Only use power units with safe galvanic isolation
(e.g. SELV).

Liquiphant M FTL51C

1 = F = T 50 mA

2 = PLC, AI modules,...

Output signal

~ 16 mA

~ 8 mA

L00-FTL2xxxx-07-05-

Signal on alarm Output signal on power failure or in the event of damaged sensor: < 3.6 mA

Connectable load • R = (U - 11 V) : 16.8 mA

• U = connection voltage: DC 11 to 36 V (in wet environments DC 11 to 35 V)

Example: PLC with 250  with 2-wire version

250  = (U – 11V) / 16.8 mA

4.2 [/] = U – 11 V
U = 15.2 V

= 16 mA ± 5 %

= 8 mA ± 6 %

= lit

= unlit

xx-xx-000

Safety mode Level Output signal LEDs

green red

10 Endress+Hauser

Liquiphant M FTL51C

1 2

FEL56

EEx ia

H

L

I

-

.

MAX

MIN

+
2 1

+
2 1

+
2 1

+
2 1

0.6 …

1.0 mA

0.6 …

1.0 mA

2.2 …

2.8 mA

2.2 …

2.8 mA

Electronic insert FEL56 (NAMUR L-H edge)

Power supply Supply voltage: DC 8.2 V ±20 %

Power consumption: < 6 mW at I < 1 mA; < 38 mW at I = 2.8 mA
Connection data interface: IEC 60947-5-6

Electrical connection Two-wire connection for separate switching unit

For connection to isolating amplifiers according to NAMUR
(IEC 60947-5-6), e.g. FTL325N from Endress+Hauser.
Output signal jump from low to high current on point level.

(L–H edge)

Connecting to multiplexer: Set clock time to min. 2 s.

Output signal

= lit

= flashes

= unlit

L00-FTL5xxxx-07-05-

xx-xx-002

Signal on alarm Output signal in the event of damaged sensor: > 2.2 mA

Connectable load See Technical Data of the isolating amplifier connected according to IEC 60947–5–6 (NAMUR)

Safety mode Level Output signal LEDs

green red

Endress+Hauser 11