The document details the features and benefits of the X57 series of intrinsic safety barriers, which limit electrical power delivered to hazardous areas, preventing explosions. It highlights the advantages of intrinsic safety design over explosion-proof designs, including easier accessibility, lower installation costs, and efficient maintenance. Additionally, it covers various barrier options, specifications, and applications while emphasizing the importance of proper compliance and installation for safety.

1. ISO 9001
R E G I S T E R E D
I n t r i n s i c S a f e t y B a r r i e r sI n t r i n s i c S a f e t y B a r r i e r s
X57

2. Intrinsic Safety Barriers are devices
which limit the power (energy) that
can be delivered from a safe area into a
hazardous area. Explosions are therefore
prevented, not just contained, as in expan-
sion proof conduit and heavy cast housings.
Not only is electrical energy (voltage and
current) held within safe limits, but also
total energy, eliminating the possibility of
an explosion due to excessive heat. The use
of barriers and a total intrinsically safe
design philosophy offers considerable
advantages from both cost and safety
standpoints.
The following features indicate the clear benefits of
choosing an intrinsically safe design instead of an
explosion-proof design, and reflect the unique features of
the Series X57 family of barriers.
◗ All system components are immediately accessible — no time
consuming opening of explosion proof housings.
◗ Personnel safety is assured because of low voltage operation.
◗ Standard wiring techniques in open cable trays or light
gauge conduit save on material and labor cost during
initial installation.
◗ Calibration and maintenance can be performed with the
system in operation.
◗ Special skill levels are not needed to open heavy housings,
to test for gas, or to shut down the process in order to
service or operate the instrumentation.
◗ Barrier replacement is accomplished by simple exchange of
plug-in modules. There is no need to disconnect wiring or
to remove ground bars.
◗ Barriers are manufactured and stocked in the U.S.A. in
Woodland Hills, California. (Los Angeles area)
◗ Multiple channels in one barrier minimize the total number
of barrier modules needed and space required.
The Ronan I.S. Barriers are plug-in modules containing
one to four channels. Up to twenty barrier modules can be
installed in a 20 position surface mounted chassis. Single
barrier surface or DIN rail chassis are also available. Each
module has eight screw terminals. The terminals are
arranged in the chassis so that four are located in the safe
area and four are located in a protected compartment for
the wiring to the hazardous area. The safe area terminals
are numbered 1 through 4 and the protected terminals
are numbered 5 through 8. These compression type screw
terminals accept up to 12 AWG wire. The safe area
terminals are connected to equipment in a location where
the sources of potential with respect to each other or to
ground do not exceed 250 Vdc or RMS. The I.S. grounding
connection for the barriers is provided by an integral,
fixed, #8 stud with self-locking nuts. Optional ground bus
bars and multi-pin cable connectors are also available.
X57Intrinsic Safety BarriersIntrinsic Safety Barriers
2

3. X57
Typical Barrier Choices:
Field Devices Barrier Choices*
Switches (dry contact) X57-128P, X57-228P,
X57-228PD, X57-228PCL,
X57-328P, X57-428P
Thermocouples X57-205S
(ungrounded only)
RTDs and Potentiometers X57-305P, X57-405P
2-Wire Transmitters X57-128N, X57-228PD
X57-228P-209P
Solenoids/Relays/LEDs X57-128P, X57-228PD
I/P Transducers X57-228PD
Strain Gauges X57-210A
Magnetic Flow Sensors X57-110A, X57-210S
and AC Sensors
Shunt Diode Zener (Passive) I.S. BarriersShunt Diode Zener (Passive) I.S. Barriers
Ronan's Zener Barriers, especially the multi-
channel versions, are a logical choice when space
and cost are the major considerations. They do not
require their own power supply, but rather provide
protection passively. Most likely, there is a barrier
that will work, and a detailed analysis of the applica-
tion will usually identify a zener barrier that is right
for the application. However, zener barriers do
require a high integrity I.S. ground. This may present
a problem, especially in older plant installations.
When the quality or availability of an I.S. ground is
questionable, the designer should consider using
active barriers.
◗ Lowest Cost Barrier Option
◗ 1, 2, 3, and 4 Channel Barriers
◗ Negative, Positive, or AC Voltage Versions
◗ Highly Reliable Fast Acting Fuses
◗ Power Supply is Not Required
◗ NO FAULT “Blown Fuse” Barrier Replacement Policy
◗ DIN Rail or Multi-Barrier Surface Mount Chassis
3.60"
(91.44 mm)
2.50" (63.50 mm)
.88" (22.35 mm)
Specifications:
Type: Shunt zener diode with non-replaceable fuses
Mounting: Plug-in (chassis required) with gold plated
connections
Wiring: All wiring and grounding is attached to the
chassis to simplify installation and maintenance
Wire Size: Up to #12 AWG
Size: (chassis not included): 3.60″ H x .88″ W x 2.50″ D
(up to four (4) channels per barrier)
Weight: (chassis not included): 5.6 ounces
Operating Temperature: -20˚C to +50˚C
Storage Temperature: -40˚C to +80˚C
Relative Humidity: 95% non-condensing
◗ With replaceable fuses, the chance
exists that the wrong type or rating of
fuse could be installed, or that the
fuses could be defeated (bypassed with
a short circuit).
◗ Circuit breakers are mechanical, and
they are therefore more susceptible to
aging, corrosion, and damage. Also,
they typically have lower accuracy
specifications.
◗ Both the replaceable fuse and the
circuit breaker designs are harder and
more expensive to manufacture.
Therefore, they cost you more money.
Ronan's zener barriers are potted
solid. This means that if a fuse is blown,
the barrier has done its job and protected
the hazardous area as it was designed to
do. It’s true the barrier can not be field
repaired. However, if you do “blow” a
barrier fuse (even if its your fault), just
contact the Ronan factory for a rush
replacement at 1/2 price. Also, for most
applications, Ronan can provide an
easily installed in-line fuse device which
can protect the barrier’s internal fuse
(See accessory #X57-FUSE).
R e p l a c e a b l e F u s e s a n d C i r c u i t B r e a k e r s v s . N o n - R e p l a c e a b l e F u s e s
* Some European applications require an “EN” designator within the part
number (i.e. X57EN-600). Contact your local Ronan sales office for details.
3

4. Typical Barrier Choices:
Field Devices Barrier Choices*
Switches (dry contact) X57-650 (dual channel)
Proximity Sensors X57-653
Thermocouples (grounded X57-606
or ungrounded)
RTDs and Poteneiometers X57-605
2-Wire Transmitters X57-600, X57-660
Honeywell Protocol X57-600H, X57-660H
Ronan, Hart, Rosemount X57-600R, X57-660R
I.S. Ground Required X57-528N
Solenoids/Relays/LEDs X57-610, X57-611(S)
I/P Transducers X57-620
In numerous applications, zener diode barriers
will either not work, or they impose constraints that
complicate system design. The series resistance, fuse
rating and maximum working voltage of a zener
diode barrier, can cause the design engineer hours
of frustrating analysis to confirm both safety and
proper system operation. Ronan's line of active I.S.
barriers eliminates much of the tedious analysis re-
quired. In some cases, the active barrier can actually
double as a signal conditioner and eliminate other
devices from the loop. These considerations, along
with the fact that no I.S. ground is required, and the
fact that most circuits are short circuit proof, has
caused the active barriers to gain popularity.
4.75" (120.65 mm)
3.60"
(91.44 mm)
.88" (22.35 mm)
Specifications:
Type: Active isolation
Power: Nominal 24 Vdc @ 50 to 100 mA
(see individual barriers specifications)
Mounting: Plug-in (chassis required) with gold plated
connections
Wiring: All wiring is attached to the chassis, to
simplify installation and maintenance
Wire Size: Up to #12 AWG
Size: (chassis not included): 3.60″ H x .88″ W x 4.75″ D
(1 to 2 channels; see individual data sheets)
Weight: (chassis not included): Approximately 6 ounces
Operating Temperature: -20˚C to +50˚C
Storage Temperature: -40˚C to +80˚C
Relative Humidity: 95% non-condensing
The concept of "Intrinsic Safety"
originated in the European markets but
is gaining in popularity all over the
world. Originally, and still the case with
some equipment, manufacturers had
their field instruments tested and
approved with a specific I.S. barrier
(Loop Approvals). This limited the
user's choices of field instruments and
barriers. The Entity Approval concept is
now becoming the standard because it
allows the user to select field
instruments and I.S. barriers from any
approved supplier. The only stipulation
is that the entity numbers of both
devices are properly matched and that
the equipment is properly installed per
the approved installation drawings.
It is important to remember that an
l.S. barrier does not make a field device
safe. The field instrument must be either
a "simple apparatus" or an l.S. device
which was certified under the entity
concept in order for it to be compatible
with Ronan l.S. barriers. If you have a
question or concern about your applica-
tion, contact Ronan for assistance.
E n t i t y A p p r o v a l s v s . L o o p A p p r o v a l
◗ Full Input, Output and Power Isolation
(Eliminates ground loops)
◗ Short Circuit Proof (Most models) or Fuse Protected
◗ No I.S. Ground Required
◗ Less Critical Circuit Design Constraints
◗ Eliminates Other Signal Conditioning, thereby
Lowering Installed Cost
◗ Discrete or Analog Input and Output Barrier Options
X57Galvanic Isolation (Active) BarriersGalvanic Isolation (Active) Barriers
* Some European applications require an “EN” designator within the part
number (i.e. X57EN-600). Contact your local Ronan sales office for details.
4

5. X57Common ApplicationsCommon Applications
5
These applications are intended as an aid in selecting possible
barrier options. As with any I.S. installation, variables such as area
classification, make and model of field device, required approval
agency certification, and total loop design can all affect safety
and operation. Therefore, care should be excercised when selecting
a barrier to assure compliance with approved installation drawings
and to assure proper circuit operations. Ronan engineers are
available to help in your barrier selection.
X57-606
+
-
24 Vdc
+
-
4-20 mA (Non-Linear)
2
46
5
T/C
Optional
Ground
X57-205S
X57-210L
Transmitter
2
4
7
5
I.S. Ground
T/C
(No Ground)
+
-
4-20 mA
+
-
24 Vdc
+
-
4-20 mA (Linear)
2
4
7
6
5
X57-605L
RTD or
Potentiometer
2
4
7
5
X57-230
Transmitter
6 3
X57-305P
4
I.S. Ground
+
-
4-20 mA
RTD or
Potentiometer
+
-
24 Vdc
4-20 mA
Controller
+
-
X57-228 PD
+
-
2
4
7
5I/P
I.S. Ground
+
-
24 Vdc
X57-620
4-20 mA
Controller
+
-
3
47
5
+
-
I/P
2
4
7
5
X57-228 PD
I.S. Ground
+
-
24 Vdc
2-Wire
Trans-
mitter
+
-
100 Ω Loop Resistor
X51-422
Trip
+
-
24 Vdc
Signal
+
-
24 Vdc
X57-600
PLC
or
DCS
+
-
3
47
5
250 Ω Loop Resistor
4-20
mA
2-Wire
Trans-
mitter
+
-
+
-
24 VdcX57-610
3
47
5
+
-
LED
or
Solenoid
2
4
7
5
I.S. Ground
X57-228 PD
+
-
24 Vdc
+
-
LED
or
Solenoid
Hazardous Area Safe AreaHazardous Area Safe Area
P A S S I V E A C T I V E
C u r r e n t / V o l t a g e D r i v e r ( D i g i t a l ) O u t p u t
T w o - W i r e T r a n s m i t t e r ( A n a l o g ) I n p u t
I / P ( A n a l o g ) O u t p u t
R T D ( A n a l o g ) I n p u t
T h e r m o c o u p l e ( A n a l o g ) I n p u t
D r y C o n t a c t ( D i g i t a l ) I n p u t
AnnunciatorX57-228 PCL
2
47
5
H
FC
+
-
24-32 Vdc
I.S. Ground
Dry Contact Annunciator
H1
FC1
H2
FC2
X57-650
1
2
3
4
8
7
6
5
+
-
24 Vdc
Dry Contact
Dry Contact

6. X57Chassis Options (Surface Mount)Chassis Options (Surface Mount)
S u r f a c e M o u n t f o r A c t i v e a n d Z e n e r B a r r i e r s
X57-SM-10 X57-SM-4
with Ground Bars
X57-SM-1
with Ground Bars
5.94 in.
(150.82 mm)
3.56 in.
(90.81 mm)
2431243124312431243124312431243124312431
C
D
B A
.91 in.
(23.11 mm)
1.71 in. (43.43 mm)
4.00 in.
(101.60 mm)
.21 in. (5.41 mm)
4 Places
I.S.
GND
V+
V–
10
9
8
7
6
5
4
3
2
1
Active
Isolated
Barrier
Module
Zener Diode
Barrier
Module
Ground Bar
Ground
Connection Clamp
18GA, Green
In/Out
1 to 4
Channels
Used
Extended
Ground
Connection
Optional
I.S.
GoundI.S.
Ground
In/Out
1 to 4
Channels
Used
Ground
Connection
Ground Bar
Clamp
Extended
Ground
Connection
Optional
Hazardous
Area
Safe
Area
24 Vdc
18GA, Green
5
6
7
8
4
3
2
1
V+
V–
6875
2431
5.80 in.
(147.32 mm)
3.57 in.
(90.68 mm)
.16 in. (93.96 mm) Dia.
4 Places
4.00 in.
(101.60 mm)
5.82 in. (147.82 mm)
2.96 in.
(75.56 mm)
2.58 in.
(65.40 mm)
.91 in.
(23.11 mm)
Active
Isolated
Barrier
Module
Zener Diode
Barrier
Module
2431
I.S.
GND
V–
V+
Ground Bar
Ground Connection
18GA, Green
In/Out
1 to 4
Channels
Used
Extended
Ground
Connection
Optional
I.S. Ground
In/Out
1 to 4
Channels
Used
24 Vdc
18GA, Green
5
6
7
8
4
3
2
1
V+
V–
I.S. Ground
6875
2431
Hazardous
Area
Safe
Area
6
X 5 7 S M - 1
X 5 7 S M - 1 0 X 5 7 S M - 4 , - 1 0 , - 1 6 , a n d - 2 0 W i r i n g
X 5 7 S M - 1 W i r i n g
MODEL NO. DIMENSION A DIMENSION B DIMENSION C DIMENSION D
X57SM-4 5.68 in. (144.27 mm) 5.28 in. (134.11 mm) 5.82 in. (147.82 mm)
X57SM-10 11.05 in. (280.67 mm) 10.65 in. (270.51 mm) 5.82 in. (147.82 mm)
X57SM-16 16.42 in. (417.07 mm) 16.02 in. (406.91 mm) 5.82 in. (147.82 mm)
X57SM-20 20.00 in. (508.00 mm) 19.60 in. (497.84 mm) 5.82 in. (147.82 mm)
X57SM-4EG 5.68 in. (144.27 mm) 5.28 in. (134.11 mm) 7.42 in. (188.46 mm)
X57SM-10EG 11.05 in. (280.67 mm) 10.65 in. (270.51 mm) 7.42 in. (188.46 mm)
X57SM-16EG 16.42 in. (417.07 mm) 16.02 in. (406.91 mm) 7.42 in. (188.46 mm)
X57SM-20EG 20.00 in. (508.00 mm) 19.60 in. (497.84 mm) 7.42 in. (188.46 mm)
Extended Ground Connection (Contact Ronan for complete model numbers)
Maximum Number of Modules (Position)

7. 4.13 in.
(104.78 mm)
5.21 in. (132.21 mm)
6.29 in. (159.64 mm)
SAFE AREA
HAZARDOUS
AREA
SAFE AREA SAFE AREA
8765 4 4 43 3 32 2 21 1 1
HAZARDOUS
AREA
8765
HAZARDOUS
AREA
8765
To I.S.
Ground
To I.S.
Ground
Optional Ground
Bar with Clamps
for Signal or Shield
Ground Access.
May be Located on
Either End
.88 in.
(22.23 mm)
.86 in.
(21.84 mm)
4.28 in.
(108.71 mm)
2.00 in.
(50.00 mm)
Optional
X57 Fuse
(Shown
2 places)
Ground Bar
X57-DIN-32
Base Assembly
DIN
Rail
Zener Diode
Barrier
Module
X57 D I N R a i l M o u n t f o r A c t i v e a n d Z e n e r B a r r i e r s
Chassis Options (DIN Rail Mount)Chassis Options (DIN Rail Mount)
DIN
Rail
6.44 in.
(163.50 mm)
5.01 in. (147.45 mm)
6.89 in. (174.88 mm)
+ +
S
A
F
E
S
A
F
E
A
R
E
A
A
R
E
A
- -
88 77 66 55 44 33 22 11
HAZARDOUS
AREA
HAZARDOUS
AREA
4.73 in.
(120.02 mm)
.83 in.
(21.08 mm)
Typical .86 in.
(22.23 mm)
2.00 in.
(50.00 mm)
Active
Isolated
Barrier
Module
Optional
X57 Fuse
(Shown
2 Places)
X57-PDIN-32
Base Assembly
88776655
44332211
++--
Optional Fuse Protection Device
The X57-FUSE device attaches to the
existing terminal blocks of any X57 chassis,
and it provides a duplicate/alternate set of
terminals for connecting the field wiring. The
X57-FUSE device contains up to 4 additional
fuses that are electronically placed in series
with a barrier’s internal fuses. By sizing the
fuses on the X57-FUSE device to values less
than the barrier’s fuse you will protect the
barrier's fuses. The smaller value fuses on the
X57-FUSE device will “blow” first, in the event
of over-voltage or short circuits.
7
X 5 7 - P D I N - 3 2 ( S h o w n ) a n d X 5 7 - P D I N - 3 5
X 5 7 - D I N - 3 2 ( S h o w n ) a n d X 5 7 - D I N - 3 5
X57-P DIN-32
for Active Barriers
X57-DIN-32
with Ground Bars
for Zener Barriers
The X57-PDIN chassis was designed for use
with X57-600 Series (active) barriers only.
These chassis do not have safety ground con-
nections. Therefore, they can not be used
with zener barriers. Each chassis has a set of
terminals for connecting 24 Vdc power. In
multiple barrier applications, “+” and “-”
power wires must be connected separately to
each chassis or “daisychained” from chassis to
chassis. On large systems, consider using the
surface mount chassis to simplify power
connection wiring.
Note: The X57-DIN-32 and X57-PDIN-32 use 32mm “G” style rails.
These chassis are also available for the 35 x 7.5 mm and 35 x 15 mm
“U” style rails. Order X57-DIN-35 or X57-PDIN-35.
Contact Ronan for availability.
The “DIN” rail chassis options are an ideal
choice to save on panel space. Order one
chassis for each barrier module. With the
X57-DIN chassis (for zener barriers) each
chassis requires its own ground wire. On
multiple chassis installations, the optional
ground bars “buss” together the individual
chassis grounds allowing one ground con-
nection for the entire group. These ground
bars and the ground bar clamps also provide
a convenient spot to terminate cable shields.
Contact Ronan for assistance in specifying
ground bars for your installation. On larger
systems, consider using the surface mount
chassis to simplify ground wiring.

8. Ronan warrants equipment of its own manufacture
to be free from defects in material and workmanship,
under normal conditions of use and service,
and will replace any component found to be defective,
on its return, transportation charges prepaid,
within one year of its original purchase.
This warranty carries no liability,
either expressed or implied, beyond our obligations
to replace the unit which carries the warranty.
R O N A N E N G I N E E R I N G C O M P A N Y
I / O P r o d u c t s D i v i s i o n
21200 Oxnard Street, Woodland Hills, CA 91367 U.S.A.
800-327-6626 • Fax 818-992-6435
1 Tilley Road, Crowther Industrial Estate, Washington, Tyne & Wear U.K., NE38 OAE
44-191-416-1689 • Fax 44-191-416-5856
32 Bermondsey Road, Toronto, Ontario, Canada M4B 1Z5
416-752-0310 • Fax 416-752-8072
h t t p : / / w w w . r o n a n . c o m E - M a i l : s a l e s @ r o n a n . c o m
X57 Rev.0 10/98 Printed in U.S.A.
W a r r a n t yW a r r a n t y