Contacts
- intro
Overview TRIM TRIO and SEALOK contacts
Selection matrix TRIM TRIO and SEALOK contacts
CONTACTS
99
Contacts
Current ratings for multi-contact connectors
Choice of right connector -
contact combination.
The choice of a Trim Trio connector in
combination with a Trim Trio contact is
essential and different for any application
There is considerable misunderstanding in
the field on current carrying capabilities for
the various contacts in the TrimTrio
programme.
The intention of this part is to give guidance
how to interprete the given current ratings in
general and how to calculate them for
particular applications.
The information given is based upon existing
MIL specifications such as:
MIL-C-26482, MIL-C-8384,
MIL-T-7928, MIL-W-5086,
MIL-W-5088, MIL-W-16878, etc. and in
conjunction with long field practice.
Table 1 - Current carrying capabilities per wire size
AWG
wire size
mm
2
0.13
0.20
0.32
0.52
0.82
1.30
2.10
wire dia.
mm
Amp.
0.40
0.51
0.64
0.81
1.02
1.29
1.63
max.curr.
carrying
Amp.
3
4.5
9
11
16
22
32
max.oper-
ating curr.
Amp.
2
3
5
7.5
10
13
17
recomm.
cont. curr.
1
2
3
5
7.5
10
13
26
24
22
20
18
16
14
Table 2 - Current carrying capabilities per contact type
size
pin dia.
type
max. curr.
carying
Amp.
22
22
max. oper-
ating curr.
Amp.
13
13
recomm.
cont. curr.
Amp.
10
10
Current carrying capabilities
Trim Trio contacts are designed to carry a
specific current, in accordance with the
applicable specification.
This specification will be defined by
following variables:
• Connector size
The more contacts in a connector, the less
current per contact can be loaded.
• Wire size
(see table 1)
The cross section will determine the internal
resistance and temperature rise for a given
current.
-Table 1 gives the current ratings for the
various wire sizes commonly used with Trim
Trio contacts.
• Current rating
(see table 2)
The current load for a given application will
generate heat.
- Table 2 gives the
maximum current
carrying capacity
of most of the Trim Trio
contacts,
the maximum operating current
and
the recommended continuous current.
• Ambient temperature
The combination of the connector size, the
wire size and the current rating will generate
a temperature rise.
This temperature rise + a given ambient
temperature may not exeed the maximum
operating temperature of the connector
material (see performance characteristics for
each connector family).
16
.062*
1.6 mm
.040*
1.0 mm
20
RM / RC
machined
SM / SC
2 piece
stamped
SM-W / SC-W
2 piece
stamped
11
7.5
5
•
Max. current carrying capacity
•
Max. operating current
•
Recommended continuous current
What do these values mean in practice ?
•
Max current carrying capacity
of a contact is defined by the conducting
section of the contact in its smallest area.
The listed values are obtained from several
tests in laboratories under room conditions
(21°C). The contact is considered to be in
free air.
•
Max operating current
is the current with which the contacts can
be energized during a longer or shorter
period, without deteriorating and depending
on working conditions.
These are dissipated heat, cooling
provisions, ambient temperature, insulation
material, etc.
•
Recommended continuous current
can be applied for all normal cases and
working conditions. The values include a
safety margin. However, there are
restrictions in the application of the given
values. The most important restriction is the
used wire, its sectional area, insulation
temperature range, as well as wires in
bundles.
Military specifications require that for a
cable bundle of 15 conductors or more, the
bundle shall not carry more than 20% of the
total carrying capacity of the bundle.
In smaller bundles, the allowable percentage
of total current may be increased as the
bundle approaches the single wire condition.
This percentage of increase in total current
carrying capacity of the bundle is 6% for
each conductor less than 15 in a bundle.
100
Contacts
From simple calculations, one can see that
the closer the bundle approaches the single
wire condition, the higher the allowable
current per conductor becomes, to even
such an extent, that it exceeds the
recommended continuous current value. In
that case, the recommended continuous
value should have preference. In order to
make this clear, we will give hereafter some
typical examples.
• Example 1
Cable bundle, 48 conductors AWG20
(0.5mm
2
) used with circular TrimTrio
connector with insert arrangement
24-48 and machined size 16 contacts
RM/RC20.
- Total operating current capacity of
bundle 48 x 7.5 A ( table I) = 360 A
- Total allowable capacity for bundles of
more than 15 wires is 20% = 72 A
- When all conductors are energized
equally, this gives:
72 : 48 = 1.5 A per conductor
When for instance 5 conductors are
energized to the recommended continuous
current of 5 A (see table 1) resulting in 25 A
consumption, the other conductors may not
take more than
72 - 25 = 47 A all together, or 1 A per
conductor.
Any other combination can of course also be
taken as long as the total capacity of 72 A is
not exceeded and the recommended
continuous current is respected.
Remark
Please note that contacts used are of the
size 16 type with maximum operating
current of 13 A (table 2).
The maximum operating current of the
bundle is however restricted to 7.5 A per
conductor due to the wire size of AWG20
(see table 1).
• Example 2
Cable bundle, 14 conductors AWG22
(0.32 mm
2
) used with rectangular
Trim Trio connector with insert arrangement
for 14 contacts, and machined size 16
contacts RM / RC20.
- Total operating current capacity of
bundle 14 x 5 (table I) = 70 A
- Total allowable for wire bundle of 15
wires less 1 is 20% + 6% = 26%
gives 18.2 A.
- All conductors energized equally, gives:
18.2 : 14 = 1.3 A per conductor
This value is within the recommended rating
of 3 A so that it can be applied.
See also remark under example 1.
• Example 3
Cable bundle, 4 conductors AWG16
(1.3mm
2
) used with circular Trim Trio
connector with insert arrangement 10-4 and
stamped 2 piece contacts
SM /SC.
- Total operating current capacity of
bundle 4 x 13 A (table I) = 52 A
- Total allowable for wire bundle of 15
wires less 11 is 20% + 66% = 86%
gives 44.7 A.
- All conductors energized equally, gives:
44.7 : 4 = 11.2 A per conductor
Since the recommended continuous current
is 10 A, the conductor should not carry more
than 10 A individiually.
As said before, the recommended ratings are valid for most common wiring systems and
under normal working conditions. For extreme conditions, the given values should be
lowered. The percentage of current reduction should be investigated from case to case.
A rule-of thumb which can be used for such cases is:
4 Amp. per mm
2
wire section
It gives us for common used wire sizes the values listed in table 3.
Table 3 - Recommended continuous current for extreme working conditions
AWG
wire size
mm2
recommended
continuous
current
Amp.
0.5
0.8
1.3
2.0
3.3
5.2
8.4
26
24
22
20
18
16
14
0.13
0.20
0.32
0.52
0.82
1.30
2.10
101
CONTACTS
Contacts
Crimping instructions
The conductor and insulation crimp
section
Are designed to accommodate wire-
conductor and insulation diameters,
expressed in AWG (American Wire Gauge)
or mm
2
.
For each wire gauge, a correct crimp
requires a crimp height that offers the
highest performance.
This performance is defined as the highest
tensile strength force.
A good conductor crimp can be guaranteed
if the tensile stength force is equal or higher
as indicated on the graph below. E.g. a
conductor of AWG20 (0.52 mm
2
) has a good
crimp if the tensile strength is min 84N.
The tensile strength force is measured in
Newtons and is the wire-to-contact
connection that will withstand when a
straight axial load is applied to the
terminated wire. This is however a
destructive test and is therefore
inappropriate as a 100% inspection method.
An alternative method is to measure crimp
height. The crimp height is measured at the
conductor-crimp section.
•
If the dimension is to small,
then the
conductor is over-crimped and the wire
strands could be damaged, which results
in a lower tensile strength force.
•
If the dimension is to large,
then the
conductor is under-crimped and the wire
strands will not be deformed enough to
assure that the crimp will pass the tensile
strength test.
In both cases, the application tooling’s
crimp height should be adjusted.
In order to have the right tooling’s crimp
height go and no-go gauges can be
obtained and are defined in function of the
type of crimp tooling and the wire gauge.
For further information consult factory.
102
RM/RC
- Machined contacts
Size 16 solid machined
contacts for TRIM
TRIO connectors
Description
Size 16 RM/RC .0625” (1.6mm) diameter
contacts are precision solid machined crimp
snap-in pin and sockets for heavy duty top
performance requirements.
Springs on both contacts are made of
spring-tempered, heat-treated, beryllium
copper.
The socket inner spring supplies high
contact pressure to ensure low-resistance
contact between pin and socket. The socket
contact features closed entry to prevent
probe damage. Crimp barrels have
insulation grips for vibration support and are
provided with a cable stop and inspection
hole.
Features and benefits
• Made from high conductive copper alloy
with gold or tin over nickel plate finish.
• Heat-treated beryllium copper locking
springs assure proper locking and
alignment of contacts in the housing.
• Colour coded for different wire sizes.
• Closed entry design on socket contact to
prevent probe damage.
• Contacts available in bulk packing
Construction
Contact body: High conductive copper alloy.
Outer spring: Tempered, heat-treated,
non-plated beryllium copper.
Inner spring socket: Tempered, heat-treated,
plated beryllium copper.
Connector accommodation
Any TRIM TRIO contact can be used in any
contact position in any connector in the
TRIM TRIO interconnection system.
• MS-M Rectangular connectors
• SMS Qikmate
• PI43 Eurorack connectors
• UT-Bantam
• UTG Metalok bantam
• UTP Full plastic bantam
• UTGS Shielded bantam
• MBG Bantamate II
Plating table
K (std) = Min. 0.4 µ Gold all over,over Nickel
J
= Gold flash all over, over Nickel
N = Min. 0.75 µ Gold all over,over Nickel
T
= 3 - 5 µ Tin all over, over Nickel
Other platings on request
Performance characteristics
Current rating:
Contact resistance:
Operating voltage:
Contact retention in body:
Individual insertion force:
Individual withdrawal force:
13 Amp
3 mΩ
750 V RMS
110 N min.
3.5 N max.
0.55 N min.
How to order
(K) RM
(K) RC
Contact type:
RM:
RC:
KRM:
KRC:
Male contact bulk packing
Female contact bulk packing
Male contact on plastic carrier strip
Female contact on plastic carrier strip
16
16
M
M
23
23
(GE1)
(GE1)
K
K
–
–
AWG Size:
Size 16:
Design variation:
Grounding contact:
Plating indication:
Packing quantity:
16, 20, 24, 28
.0625” (1.6mm) Diameter contacts
Crimp barrel
See plating table
No digit (std) : 50 pcs. bulk packing (RM/RC)
: 2000 pcs on reel (KRM/KRC)
1000 : 1000 pcs bulk packing (RM/RC)
103
RM/RC
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