opticalCON camera applications
using hybrid SMPTE cables where
voltage exceeds 50V
Contents
1
Scope .................................................................................................................................................. 3
OBJECT....................................................................................................................... 3
2
3
4
Normative background ........................................................................................................................ 3
2.1
Overvoltage category according to IEC 60664-1 .................................................................. 3
2.2
Pollution degree according to IEC 60664-1........................................................................... 3
2.3
Insulation type according to IEC 60664-1 ............................................................................. 4
2.4
Clearance .............................................................................................................................. 4
2.4
Creepage distance ................................................................................................................ 4
Insulation coordination according IEC 60664-1 for opticalCON® interconnections ........................... 4
3.1
Applicable parameters according to IEC 60664-1 for opticalCON® interconnections .......... 4
3.1.1 Overvoltage category ................................................................................................................. 4
3.1.2 Pollution degree ......................................................................................................................... 4
3.1.3 Insulation type ............................................................................................................................ 4
3.1.4 Clearance and Creepage distance ............................................................................................ 5
3.2
Clearance of opticalCON® chassis connectors .................................................................... 5
3.3
Creepage distance of opticalCON® chassis connectors ...................................................... 5
3.4
Clearance of opticalCON® cable connectors ........................................................................ 5
3.5
Creepage distance of opticalCON® cable connectors .......................................................... 6
Protection against electric shock ........................................................................................................ 6
4.1
Camera safety circuits ........................................................................................................... 6
4.2
Neutrik approved camera systems ........................................................................................ 6
Conclusion .................................................................................................................. 6
5
Requirements ...................................................................................................................................... 6
5.1
Camera system...................................................................................................................... 6
5.2
Facility.................................................................................................................................... 6
5.3
Cable assembly ..................................................................................................................... 6
5.4
Chassis connector assembly ................................................................................................. 7
Neutrik AG
Im alten Riet 143
9494 Schaan
Liechtenstein
Author: Christian Ganahl
© Copyright 2012 Neutrik AG.
All rights reserved.
Document: NWP02, Version 4.1
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OBJECT
1 Scope
2 Normative background
Professional broadcast / film production cameras
increasingly offer fiber optic interconnections.
Hybrid fiber-plus-copper cables (so called
SMPTE cables) commonly transmit the camera
signal (using fiber optic strands) plus camera
power (via copper) of up to 400V. The existing
standards for this transmission are SMPTE 311
for the hybrid cables and SMPTE 304M for the
camera connectors. Routing several camera
interconnection areas (studios, most commonly)
and control rooms (connected to camera control
units, called CCUs) with the help of a camera
cable patch field became a common approach to
cut down on costs and to increase flexibility within broadcast and film production studios.
SMPTE 304M defines a max voltage of 600 V for
camera connectors. Some camera manufacturers (Sony, Ikegami, Grass Valley, Hitachi, Panasonic, ...) work with CCU output voltages of up to
240 VAC or 400 VDC. IEC 60664-1 defines the
safety requirements for insulation coordination
applicable to such connections.
Critical values are clearance and creepage distance based on possible overvoltage, protective
earth structure, conductive pollution, humidity,
expected condensation, connector insulation
material, etc.
2.1
Interconnection problems and high maintenance
efforts caused by traditional SMPTE 304M camera connectors have led many users to choose
non-standardized hybrid connectors, such as
Neutrik’s opticalCON® for wallplates, patch
fields, and comparable appliances.
The IEC 60664-1 defines the following for
equipment energized directly from the lowvoltage mains1):
- Equipment of overvoltage category I is
equipment for connection to circuits in which
measures are taken to limit transient overvoltage to an appropriately low level.
- Equipment of overvoltage category II is energy-consuming equipment to be supplied
from the fixed installation.
- Equipment of overvoltage category III is
equipment in fixed installations and for cases
where the reliability and the availability of the
equipment is subject to special requirements.
- Equipment of overvoltage category IV as for
use at the origin of the installation.
2.2
Neutrik opticalCON® is not approved for voltages > 50V. However it may be used for indoor
applications on higher voltage.
Pollution degree
IEC 60664-1
according
to
The degree of pollution in the micro environment
is basically a function of humidity, expected condensation and conductive pollution. Four pollution degrees are defined in the IEC 60664-1
standard 1):
- Pollution degree 1
No pollution or only dry, non-conductive pollution occurs. The pollution has no influence.
- Pollution degree 2
Only non-conductive pollution occurs except
that occasionally a temporary conductivity
caused by condensation is to be expected.
- Pollution degree 3
Conductive pollution occurs or dry nonconductive pollution occurs which becomes
conductive due to condensation which is to
be expected.
- Pollution degree 4
The pollution generates persistent conductivity caused by conductive dust or by rain or
snow.
Extract of the Neutrik Website www.neutrik.com:
“Not compatible to SMPTE 304M standard. Suitable for indoor (studio) camera links considering
specific conditions acc. to IEC 60664-1 like pollution degree 1, overvoltage category 1 and rated voltage.”
This paper covers the limitations of the opticalCON® connection system when used for a hybrid fiber optic camera – CCU (camera control
unit) link / patching application with voltages >
50V.
The standard SMPTE 304M defines the electric
strength requirements of camera connectors.
Even though opticalCON® does not meet all of
the requirements of this standard, it may be used
for limited applications.
Document: NWP02, Version 4.1
Overvoltage category according to
IEC 60664-1
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2.3
Insulation
type
IEC 60664-1
according
* … Clearance of reinforced insulation shall be
dimensioned as specified in table 2 corresponding to the rated impulse voltage but one step
higher in the preferred series of values than that
specified for basic insulation.
to
IEC 60664-1 defines material groups based on
the CTI (comparative tracking index) of insulation materials. The material only affect values at
pollution degree >1 (see 2.2).
2.4
The creepage distance cannot be proven by test
and must meet the defined minimums according
IEC 60664-11) (for pollution degrees 2 and 3 the
worst case material group is assumed):
Required contact clearance and creepage distance are related to insulation types according to
IEC 60664-1.
Insulation is grouped into five types 1):
- Functional insulation
- Basic insulation
- Supplementary insulation
- Double insulation
- Reinforced insulation
Creepage distance to avoid failure due tracking:
Minimum creepage distances based on 250
VDC; Extract IEC 60-664-1 table 4
Pollution degree
1
2
3
Basic insulation 0.56 mm
2.5 mm
4 mm
Reinforced ins.* 1.12 mm
5 mm
8 mm
For the application discussed in this paper
“basic” or “reinforced” insulation would be applicable. The following definitions are defined in
IEC 60664-11):
- Basic insulation
Insulation applied to live parts to provide
basic protection against electric shock.
- Reinforced insulation
Insulation of hazardous-live parts, which
provides a degree of protection against electric shock equivalent to double insulation.
*… Creepage distance for reinforced insulation
shall be twice those determined for basic insulation.
Creepage distances less than the clearance
required in case A of table 2 may only be used
under conditions of pollution degrees 1 and 2
when the creepage distance can withstand the
voltage required for the associated clearance.
“Basic insulation” may be applied between hazardous and accessible conductive parts if the
latter parts are reliably connected to a protective
earth terminal; if this cannot be guaranteed, then
“Reinforced insulation” must be applied.
2.4
Creepage distance
3 Insulation coordination according
IEC 60664-1 for opticalCON® interconnections
Clearance
3.1
The contact clearance must withstand the required impulse withstand voltage. Based on table 1 of IEC 60664-1, the rated impulse withstand voltage of 1500 V (overvoltage category I)
can be applied for supply systems up to 300 V
rated voltage1):
3.1.1 Overvoltage category
Camera control units of professional broadcast /
film production cameras offer overvoltage protected circuits complying with category I as defined in the IEC 60664-1 standard. (see 2.1)
Clearance to withstand transient voltages:
Minimum clearance based on 1500 V impulse
voltage; Extract IEC 60-664-1 table 2
Case “A” inhoPollution degree
mogeneous
1
2
3
Basic insulation
0.5 mm
0.5 mm 0.8 mm
Reinforced ins.*
1.5 mm
1.5 mm 1.5 mm
3.1.2 Pollution degree
The design of the opticalCON® interconnection
system is limited in contact distance. Clearance
as well as creepage distances according to IEC
60664-1 can only be achieved with pollution degree 1. (see 2.2)
Clearance values smaller than defined in table 2
require verification by test 1):
3.1.3 Insulation type
Based on 3.1.2 only pollution degree 1 can be
applied for opticalCON® interconnection systems
which eliminate the need for considering an insulation material group.
Camera control units are connected to PE (protective earth), the camera is connected to PE
over the cable shield of SMPTE 311 hybrid cables. Thus a closed protective circuit is created.
Nevertheless this link may not be technically
Test voltage for verifying clearances at sea level
Impulse test voltage at sea level based on 1500
V impulse voltage; Extract IEC 60-664-1 table 5
Impulse voltage
U rated
U test
Basic insulation
1.5 kV
1.75 kV
Reinforced insulation*
2.5 kV
2.95 kV
Document: NWP02, Version 4.1
Applicable parameters according to
IEC 60664-1 for opticalCON® interconnections
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valid since the camera is not grounded to PE
individually and the cable shield does not necessarily fulfil the requirements of a PE conductor.
For this reason “reinforced insulation” must be
taken as the base for clearance and creepage
distance selection according to IEC 60664-1
(see 2.3)
quired impulse withstand voltage of 2.95 kV (see
evaluation at 3.1.4)
Impulse test for verifying clearances:
3.1.4 Clearance and Creepage distance
3.3
A.C. withstand voltages at altitude 500 m
Contact 1-2 / 3-4
3.6 kV
Contact - Shield
4.1 kV
All professional fiber camera systems except for
the Grass Valley LDK series work on voltages <
250V a.c.. Hence, a max voltage of 250 V is
chosen for the evaluation of clearance and
creepage distances according to IEC 60664-1:
 Rated impulse withstand
voltage based on reinforced ins.= 2.5 kV
 Clearance based on Case “A”, pollution
degree 1 and reinforced insul. = 1.5 mm
 Impulse test voltage = 2.95 kV
 Creepage distance based on pollution
degree and reinforced insul. = 1.12 mm
3.2
Creepage distance of opticalCON®
chassis connectors
The most critical position for creepage distance
is shown in Fig. 2. Here the creepage distance
between the contacts and the connector shell
exceeds the minimum requirement of 1.12mm
(see evaluation at 3.1.4)
Clearance of opticalCON® chassis
connectors
SMPTE 311 cables are by definition to be wired
as follows:
Contact 1 = power (-)
Contact 2 = sense (ELV signal < 50V)
Contact 3 = sense (ELV signal < 50V)
Contact 4 = power (+)
Housing = shield (PE)
Hence the critical clearance must be investigated between contacts 1 and 2 as well as 3 and 4
and, finally from contact 1 and 4 to the connector shell
Figure 2
3.4
As shown in Fig. 1 the min. clearance of 1.5mm
(see evaluation at 3.1.4.) between contact 1 and
2 as well as 3 and 4 cannot be achieved.
Clearance of opticalCON® cable
connectors
As shown in Fig. 3 the minimum clearance of
1.5mm (see evaluation at 3.1.4.) between contacts 1 and 2 as well as 3 and 4 cannot be
achieved.
Figure 1
Hence an impulse test according to 2.4 must
prove that the contact clearance meets the re-
Document: NWP02, Version 4.1
Figure 3
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Hence an impulse test according to 2.4 must
prove that the contact clearance meets the required impulse withstand voltage of 2.95 kV (see
evaluation at 3.1.4)
Sony:
HDCU 1500 Base Station
HDC 1400 HD-Camera
HDCU 1700 Base Station
HDC 1700 HD-Camera
HDCU 2500 Base Station
HDC 2400 HD-Camera
Impulse test for verifying clearances:
A.C. withstand voltages at altitude 500 m
Contact 1-2 / 3-4
3.6 kV
Contact - Shield
4.1 kV
3.5
Ikegami:
CCU-890 Base Station
BS-89 Base Station
HDK-79EXIII HD-Camera SE-H700 Optic
OCP-200 Operation Control Panel
Creepage distance of opticalCON®
cable connectors
Hitachi:
Z-HD5000 Camera
SKHD 1000 Camera
SKHD 1200 Camera
SKHD 2000 Camera
SKHD 2200 Camera
CU-HD 1000 Base Station
CU-HD 500 Base Station
The most critical position for creepage distance
is shown in Fig. 4. Here the creepage distance
between the contacts and the connector shell
exceeds the minimum of 1.12mm (see evaluation at 3.1.4).
CONCLUSION
The opticalCON® interconnection system may
be used for professional broadcast / film production cameras considering the requirements defined below:
5 Requirements
5.1
Figure 4
The following requirements must be fulfilled in all
cases:
4 Protection against electric shock
4.1
Camera safety circuits
-
Every Neutrik approved camera system (find list
of approved systems at 4.2) offers a safety circuit. No power exceeding ELV (extra low voltage; max 50V) is applied to the system as long
as any connector of all of the cables in the link
used between the camera control unit and the
corresponding camera is unmated.
This system guarantees safety against electric
shock.
4.2
-
5.2
The maxiumum rated voltage output power
of the camera control unit is 250 V a.c. / d.c.
Protection against electric shock must be
provided with a start-up safety circuit
The camera system must meet overvoltage
category I (see 2.1)
Facility
The user must guarantee facility conditions according pollution degree 1 (see 2.2).
Neutrik approved camera systems
5.3
All of the following approved camera systems
have been tested by Neutrik AG. Camera systems not listed below must be tested and approved by Neutrik before use. For camera systems that require qualification contact information may be found at www.neutrik.com
Document: NWP02, Version 4.1
Camera system
Camera systems shall be approved by Neutrik
AG. Find list of approved camera systems at 4.2.
Contact Neutrik for approval of non-listed systems.
Cable assembly
All cables assembled by Neutrik meet the requirements as defined in this document and are
100% voltage proof tested with 1.5 kV d.c..
Neutrik recommends a 100% voltage proof test
of all SMPTE cables for all certified assemblers.
Shrink tubing must be applied at least on contact
1 and contact 4 and must fully cover the contact
as close as possible to the insulator.
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5.4
Chassis connector assembly
NO2-4FDW-1-A connectors offer stepped contacts as shown in Fig 5 and meet the requirements as defined in this document.
Contact 1
Contact 4
Figure 5
Shrink tubing must be applied at least on contact
1 and contact 4 and must fully cover the contact
isolation tube.
Neutrik, in addition, recommends to avoid pollution of the chassis connectors (as required for
pollution degree 1) by protecting the contacts
with the rear cover SCDR, which should ideally
be filled with silicon, and the front sealing cover
SCNO-FDW-A (see Figure 6 & 7)
Figure 6 (SCDR)
Sources:
1 Abstract of IEC60664-1
Standard references:
-
Figure 7 (SCNO-FDW-A, mated)
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IEC 60664-1
IEC 536
SMPTE 311
SMPTE 304M