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Basic
Construction :
elmex Teminal Blocks are
mounted on 35,32 or 15 mm Standard Rails types TH35, G32,
Th15 (Iec60715) or Ts35, Ts32, Ts15 (DIN EN Standard).
The terminal blocks have a modular design, so that they
can be installed side by side, simply by clipping-on to
form a uniform assembly on mounting rails. This feature
yields simplicity, economy and compactness in installation,
and allows for desired future extensions. |
| |
A typical Feed-through terminal
block consists of: |
| 1.0 |
Insulated
Housing: Standard Design with |
| 1.1 |
Polyamide
6.6 |
| 1.2 |
Melamine |
| 2.0 |
Conductor Clamping :
Standard Designs with |
| 2.1 |
Screw
Clamps – steel |
| 2.2 |
Screw
Clamps –spring Loaded |
| 2.3 |
Screw
Clamps – Copper - Alloy |
| 2.4 |
Spring
Clamps |
| 2.5 |
Stud-and-nut
clamping for cable lugs |
| 3.0 |
Current
Bar : Current carrying part of Terminal Block |
| 4.0 |
Mounting
Springs: For mounting on 32mm rail (TS 32/G32), in case
of Melamine Housings. |
| elmex terminal blocks
can accept solid and standard conductors as well as flexible
conductors of size up to rated connection capacity, as
specified in the detailed specification sections of this
catalogue. |
| The
above basic construction is developed further into various
individual types of Terminal Blocks for different applications,
such as multilevel types, Earth Terminals Distribution
Blocks, Fuse feed through types, Component Housing types
etc. |
Panel Mounting type,
Wire Wrap type, Terminal type etc., have different designs
for connection
of conductors and are described under respective sections,
of this catalogue. |
1.0 |
Insulated Housings |
| |
Two types of insulated housing
are employed in elmex terminal blocks |
1 |
Thermoplastic : Polyamide 6.6,Injection
Moulded |
2 |
Thermosetting : Melamine ,Compression
Moulded |
| Polyamide
6.6(or Nylon 6.6) is a resin belonging to the Nylon
family of thermoplastic mounding materials. |
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Polyamide 6.6 possesses a good balance of various properties
:- tensile and flexural strengths ,allowable service temperature,
impact resistance, abrasion resistance, resistance to
fuels, lubricants and many chemicals(except strong acids
and oxidizing agents).It has good electrical properties
,for low voltage applications. It is resistance to surface
discharge with CTI > 600(IEC-60112). |
| |
 Melamine
is a resin belonging to the group of thermosetting compounds,
generally known as aminoplasts. It has an excellent resistance
to deformation, particular hardness and a very good surface
brilliance.
Melamine has an optimum dimensional stability and a strong
resistance to surface discharge with CTI > 600 (IEC-60112).It
does not ignite and gets converted into char from in case
of fire. It is abrasion and chemical resistant, waterproof
and resists high and low temperatures within the limits
of -40 C and 130 C
Melamine is particularly suited for use in severe environmental
conditions and is preferred for Circuit Breaker Panels
,Refineries, Chemical Plants, Potentially explosive installations
and any other high risk environments in general. |
2.0 |
Conductor Clamping |
2.1 |
Screw
Clamp (steel) |
|
2.1.1
Contact clamp : |
| |
elmex Screw clamp
consists of a U-shaped steel part ,called contact clamp
and a washer base or cheese head screw. |
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 The
vertical arms of the contact clamps are folded at the
top end into lips, overlapping each other. The lip from
each arm locks into recess provided on the other arm.
This double locking is an outstanding feature of elmex
screw clamp design, which allows tightening torques in
excess of the values specified by the standards. In addition,
in the event of inadvertent over tightening,this design
prevents damage to the threads and deformation of contact
clamps. |
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The button face of the ‘U’
has serrations, which grips the conductor firmly during
tightening. The lips are drilled and threaded coaxially
in a special machine to produce rolled threads for higher
mechanical strength of threads which can take higher tightening
torque. |
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The Contact clamp undergoes Heat
Treatment for increased hardness and strength. It is then
Zinc plated and passivated to a higher degree of plating
thickness than usually adopted. elmex screw
clamps therefore have a very good resistance to normal
atmospheric corrosion. |
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Heat Treatment: elmex
contact clamps are subjected to a special heat treatment
process ensuring uniformity of temperature over the entire
clamp surface and consistent results of heat treatment
so that the inner threads of the clamp achieve a uniform
and strong wear resistance. |
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2.1.2
Camping Screws: |
| |
 elmex
Screw-Clamps uses cold-forged rolled-threaded washer-base
or cheese-head screws (or Phillips-head screws in specific
cases). The screws are hardened and tempered for increased
strength and wear resistance. After first assembly they
become captive a circular ring provided in the housing
for cheese head screws. These screws are corrosion-protected
by zinc plating and passivated to a higher degree of plating
thickness, under controlled plating process. The screws
have a flat bottom which creates a balanced pressure on
current bar for conductor-clamping |
| 2.2 |
Screw
Clamp –Spring Loaded |
| |
 For
high vibration application Elmex offers spring loaded
screw clamp terminal blocks.
Although Elmex standard screw clamp design is already
resistant to vibrations, it is further strengthened against
vibrations by provision of compression springs in the
terminal block.
The springs are assembled under the contact clamp in pre-stressed
condition. When the screws are fully tightened upto specified
torque, the springs under the contact clamp provide addtional
pressure between current bar and conductor, which makes
the spring loaded terminals especially suitable for high
vibration applications.
The compression springs are made of standard spring-steel.
All other parts are some as for the screw –clamp
design. |
2.3 |
Screw
Clamp –(copper-alloy) |
|
 In
the elmex design of copper alloy terminal blocks, the
steel screw-clamp is replaced by copper-alloy screw-clamp
protection against atmospheric corrosion of copper-alloy
is achieved by tin plating to a higher degree of plating
thickness, in a controlled plating process. The tin plating
has under-coat of nickel plating to prevent zinc migration. |
|
By appropriate
selection of materials and processes, the phenomenon of
the stress corrosion cracking is taken care of in elmex
copper-alloy screw clamp. |
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The clamping part
in elmex screw clamp is of special design,
such that as the conductor clamping is achieved by tightening
of screw, the top-portion bends elastically, so that screw
threads are gripped to prevent loosening. |
2.4 |
Spring
Clamps |
|
 elmex
spring clamp consists of specially shaped stainless steel
clamp, which functions as a spring for developing necessary
contact pressure between current bar and conductor current
bar is the current bar is the current carrying part in
the terminal block, and it is provided with serrations
to grip the conductor. |
|
The spring clamp
is brought under tension by inserting a screwdriver. This
creates necessary opening in the clamp for inserting conductor
after the conductor is fully inserted the screwdriver
is withdrawn. The clamp are thereby presses the conductor
firmly against current bar, by spring action of the clamp. |
2.5 |
Stud-and
–Nut Clamping for Cable-Lugs |
|
 This
conductor-clamping design is especially developed for
receiving Ring-type or Fork-type cable lug. The terminal
block consists of housing, Studs and nuts and the current
bar. The ring type lugs can be inserted under Nuts. |
|
 The
lugged cables are clamped to the current bar by tightening
the nuts standard spanner can be sued case of “Nut-Driver”
type of stud terminals for screwdriver operated stud terminals.
For screwdriver operated stud terminals, the stud is provided
with a special long nut with a slat at the top for screwdriver.
This type is especially developed where space-limitations
may not allow the use of spanner for clamping cable-lugs |
|
All the metal parts in these types
of terminals are made of copper alloy and fun plated with
nickel under coat for protection against atmospheric corrosion. |
3.0 |
Current
Bar |
|
 elmex
current bars are made of electrotytic copper or a high
quality copper alloy and tin plated with higher than usual
plating thickness, to maintain the contact surface free
from atmospheric corrosion. Nickel under coat prevents
zinc migration in case of copper alloy current bars. |
|
Special feature of elmex current
bars is the provision of longitudinal serrations to grip
the conductor which tightening and cut into thin oxide
film of conductor the contact resistance remains very
low, once the conductor is firmly clamped. |
4.0 |
Mounting
Spring |
|
 The
spring used in melamine terminal block for fixing them
on the Rail is made of high grade stainless steel to retain
the spring tension over a longer period. The design of
there terminal housing incorporates a notch so as to provide
a self-locking mechanism to prevent the spring from slipping
out of the housing. |
