CAMTECH/S/2001/EKT(R)/1.0
1
ELECTRICAL KEY TRANSMITTER
(ROTARY TYPE )
1.
Introduction
To control points, signals & level crossing gates, the simplest way is to keep it locked at site.
Whenever its operation is required a key may be issued to operating man. He will open the
locks of these gears and operate them. After each operation key must be returned back to
controlling agency.
Considerable time is lost in physical transmission of the key from controlling agency to the
controlled spot. Greater the distance between the two, higher the time required in
transmission. To get rid of this time loss MR.HAPPER introduced an Electrical key
transmitting device known as HAPPER’s KEY TRANSMITTER (H.K.T) by his name. The
improved version of H.K.T is known as E.K.T. i.e. Electrical Key Transmitter. Another type
of EKT known as RKT (rotary type key transmitter).
2.
Type of EKT
EKT are two types as under:
i)
ii)
Happer Key Transmitter (EKT)
Electrical key transmitter Rotary Type (RKT)
This handbook covers Electrical key transmitter (Rotary type).
3.0
Working Principle:
It works on the principle of Electromagnetism & is used in pair.
„
Transmitter are fixed, one at SM’s room other with key in lock position near the
appliance which is to be controlled.
„
i)
ii)
iii)
„
i)
ii)
Transmitting end:
Key is inserted in the RKT.
Turned to R.H.S & held there.
Galvo needle gets deflected to R.H.S.
Receiving end:
Galvo needle gets deflected to R.H.S.
Seeing the deflection key is turned to L.H.S & extracted.
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
4.
Electrical Parameters (RKT):
„
„
5.
2
Electromagnet coil resistance :
Working voltage
:
15 ohms.
5 volts
Construction:
A RKT consist of two portions.
1. Outer portion
2. Inner Portion
5.1.
Outer Portion
It is essentially consist of a glass window at the top for visual indication, a key hole to
insert key for the transmission and a sealing stud to seal the equipment.
Electrical Key Transmitter
(Rotary Type)
1.
Glass Window
2.
Slotted Nut
IS2232
3.
Sealing Stud
4.
Key and Key
hole
November 2001
CAMTECH/S/2001/EKT(R)/1.0
5.2
3
Inner Portion
The RKT is of robust construction. It consist of following parts:
1
10
2
3
4
11
5
6
12
7
8
9
13
ELECTRIC KEY TRANSMITTER
(ROTARY TYPE) SA - 22601
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
4
RKT components shown in figure are as follows:
1. Indicator
2. Armature
3. Stud (S-22607)
4. Tumbler Housing Assembly (SA-22648)
5. Operating Piece (S-22655)
6. Contact Spring Assembly (SA-22678-B)
7. Quick Return Gear (SA-22669)
8. Metallic Base (S-22606)
9. Thumb Screw (SA-22604)
10. Electromagnet (SA-22617)
11. Drum Assembly (SA-22661)
12. Contact Spring Assembly (SA-22678-A)
13. Base (S-22602)
5.2.
Inner Portion:
This portion consist of metallic base (S-22606) whose parts are as under:
5.2.1
Electromagnet (SA-22617)
This is fixed in upper portion of the case. When energised, its main pole face attracts
armature which in turn helps in releasing the key, while auxillary pole face deflects
the indicator.
Electromagnet Coil
5.2.2
Contact Spring assembly (SA-22678 A-B)
It consists of five numbers of finger contacts which are insulated from each other and
make with drum assembly.
Finger contact
Of these five contacts, two contacts (No4&5)(SA-2267-B) are mounted on the left
side of the drum assembly while the other three contacts i.e. No.1,2 and 3 (SA2267A) are on its right side.
Depending upon the position of key i.e. IN, OUT or TURNED are in RKT, these
contacts make or break which in turn control the line circuit.
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
Key Position
5.2.3
5
Finger Contact
Position
Transmitting End
1. When key is “IN”
2&3, 4&5
2. When key is turn to
1&2, 4&5
RHS
Receiving End
1. For extracting key 2&3, 4&5 will make.
(Key turned to LHS)
All contacts will
2. When key is out
break.
Quick Return Gear (SA 22669)
Spring loaded quick return gear attached with the drum assembly with split cotter pin
help to force the drum assembly back to its normal or reverse position.
The gear is fixed with the thumb screw (S-22604) on the metallic base as shown in
the fig. below.
5.2.4
1.
Cotter pin
2.
Quick Return
Gear
3.
Thumb screw
Drum assembly (SA 22661)
Rotary type drum assembly provided with metallic piece help to make finger contact.
Contact 4&5
5.2.5
Contact 1,2 &3
Drum assembly
Tumbler Wards (S 22656, 22657, 22658)
Three numbers of brass tumblers control the movement of key. A proper combination
of wards and tumblers ensures that only right key can be inserted with the transmitter.
Electrical Key Transmitter
(Rotary Type)
1.
Tumbler
spring
2.
Tumbler
wards
November 2001
CAMTECH/S/2001/EKT(R)/1.0
„
5.2.6
6
Tumbler Spring (S 22660): The tumblers proving the wards of the key are to be
provided with an tumbler spring arrangement to restore them back to their normal
position before the key is extracted.
Tumbler Housing Assembly (SA 22648)
Tumbler wards 1,2 and 3 are housed under the tumbler housing assembly and hold
with LH pin (S 22659) and RH screw (IS 1366).
5.2.7
1.
Stud
2.
Tumbler
housing
assembly.
Operating Piece (S 22655)
Operating piece is placed in side the drum assembly as shown in figure below. On
operation of key, the operating piece rotates the drum assembly with the help of
extention portion provided with it.
6.0
Force drop arrangement & Lock Pawl
Operating piece
To avoid unsafe extraction of key due to residual magnetism or mechanical jamming
force drop arrangement is provided in this instrument too, as provided in other
electromagnetic signalling devices.
Force drop arrangement is provided by means of a counter weight attached with the
armature which causes the armature to drop forcefully.
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
„
7
Lock Pawl
Lock pawl engages with the drum assembly when the electro magnet is deenergised. When the electro magnet is energised, lock armature attracts and the
lock moves up and releases drum assembly.
1.
Force drop
arrangement
2.
Lock Pawl
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
7.0
8
Installation
RKT can be mounted and electrically connected in two types which are as under:
7.1
Earth return circuit:
Electrical connection and working of RKT with earth return circuit is given below:
Advantages:
• Only one line wire is required.
• Only one battery set of 12 Volt DC is required for each line relay.
• Bell circuit can be used with the same battery set.
„
Working:
Transmitting End
Receiving End
Operations:
ª Insets the key
ª Key
locked
ª Turns to RHS and receiving end.
holds
Action Initiated:
ª Contact 1 & 2, 4
& 5 make
ª Positive of
ª Positive feed
Electrical Key Transmitter
(Rotary Type)
at
November 2001
CAMTECH/S/2001/EKT(R)/1.0
battery gets connect
to line through
contact 1,2 coil and
contact 4& 5.
Transmitting End
ª Electromagnet
gets energised.
ª Needle deflects
to RHS
ª Key get locked.
9
reaches from line
through contact no. 4 &
5 at one end of coil.
ª Negative feed
reaches to coil from
earth through contact
no. 2 & 3 at other end
of coil.
Receiving End
ª Electromagnet gets
energised.
ª Needle deflects to
RHS
ª Buzzer start to
ringing to attract the
attention of operating
person or LED litup.
ª Armature attracts.
Operations:
ª Turn the key to
LHS contact 2&3 4&5
will make and extracts
it.
ª While key is
extracted all contacts
breaks. Thus line
circuit opens.
After completion of the function the receiving
end transmit the key in the same manner as
discussed above.
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
7.2
10
RKT circuit in RE area
C IR C U IT FO R R K T
ON
A C ELEC TR IFIED A R EA
Two AC immunised relay are to be used in line circuit. Underground cable is used for
the line wire. Electrical connection and working of RKT circuit in RE area is as
under.
„
Working:
Transmitting End
Operations:
ª Insets the key
ª Turns to RHS and
holds
Action Initiated:
ª Contact 1 & 2, 4
& 5 make
ª Positive of
battery connects R3
neutral relay pickup.
Electrical Key Transmitter
(Rotary Type)
Receiving End
ª Key locked at
receiving end.
November 2001
CAMTECH/S/2001/EKT(R)/1.0
Transmitting End
24 volts supply
connects to line
through front contact
of R3 relay.
11
Receiving End
ª 24 volts supply
received at
receiving end and
line relay R2
pickup through
back contact of R1
relay.
ª Buzzer starts to
ringing attract the
attention of operating
person to front contact
of R2 relay or LED lit
up.
Operation:
Turns the key to LHS
contact 4&5 2&3 will
make.
ª Electromagnet coil
gets energised with
front contact of R2(line
relay) and spring
contact of RKT 4& 5,
2 & 3 in series and key
extracted.
ª Needle deflects to
RHS.
Once key is extracts all
contact 1,2,3,4 and 5
are breaks.
After completion of the function the receiving
end transmit the key in the same manner as
discussed above.
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
8.0
12
Difference between HKT and RKT
Sr.
HKT (EKT)
RKT
1.
In HKT (Happer
key transmitter) for
key out position
some spring
contacts are
remained in make
condition (1,2)
In RKT all contacts
are in break
position at the time
of key out
condition.
2.
In HKT operating
piece is fixed with
the front cover. So
extract of the key is
possible by the
opening of the nuts
and removing the
cover with key.
In RKT opening of
he front cover and
extraction of the
key is not possible
by removing the
nuts because
operating piece is
fixed with the base,
not with the front
cover.
9.0
Maintenance
9.1
Cleanliness
• All working parts are clean and work freely.
• All contact spring are kept clean, tensioned and shaped.
9.2
Transmitter key and key holes
• All keys turn freely in the transmitter when the cover is correctly secured.
• The key hole is such that only correct key can be inserted in each transmitter and is
in proper shape.
• Check that brass tumblers are proper and not worn out.
9.3
Testing Key Transmitter
• Key transmitters are periodically tested to ensure that key can not be extracted by
jerk or irregularly.
• Check that buzzer is ringing or LED lit up properly while electrical control is
received from the other end.
• Check that indicator is deflecting properly while electrical control is received from
the other end.
• Insert key in RKT and turn to RHS and check that shelf type relay is pickup and
line voltage is going out on line while electrical control is transmitted.
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
13
• Check that in case of double key transmitter, the key for transmitting the electrical
control, released by other key mechanically get locked which is turn, not to be
released by jerks or any other irregular means.
• Check that any opening giving across to the interior of the RKT through which it is
possible to operate the mechanism by any irregular means.
• Check that once key inserted and locked in RKT, extracted of key is not possible
unless it is released by electrical control received from the other end.
• Check that correct springs contact are making when key is IN or in TURN position.
9.4
Wiring
• All wiring is in good condition and properly protected.
• All screw and nut are properly tight.
9.5
Sealing
• Check that RKT is properly sealed.
9.6
Battery
• Ensure that internal and external battery set used in RE area are separate.
• All battery must be kept clean and terminals must be free from dirt and corrosion.
9.7
Earth
• Check and ensure that earth and earth connections are effective and good condition
in case of earth return circuit is in use.
• Ensure that common earth is not used for RKT with any other circuit.
• Refer maintenance handbook on Earthing no. CAMTECH/2000/S/ETH/1.0 issued
by CAMTECH/Gwalior.
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
10.0
14
Troubleshooting
Sr Trouble
Cause
Remedy
1. Key inserted and turns to RHS and holds at
transmitting end but
Galvo needle not Galvo needle
Make clean
deflected to RHS mechanically
and free from
at transmitting
latched.
mechanical
end receiving
latching.
end.
Electrical
Check the
circuit is not
circuit and
completed.
rectify.
Buzzer or LED
Fuse for
Attend and
not ringing at
buzzer or LED replace the
receiving end.
supply blown fuse if blown
off.
off.
Buzzer or
Replace the
LED become
buzzer with
defective.
the new one.
2. Key not extracted at receiving end.
At Transmitting end.
R3 relay not
6 volts supply If blown off
pickup
fuse blown
replace the
off.
same.
If supply is
Attend and
proper check
rectify.
the RKT
contacts 1 & 2
or 4 & 5 are
not making
properly.
24 Volts supply
for line relay is
failed and not
going out.
Check 24 Volt Attend and
supply fuse.
rectify.
R3 front or
Rectify them.
arm contact of
shelf type
relay wire
termination is
loose or wire
may be cut.
24 Volts supply is proper at transmitting end.
At Receiving end.
24 volt supply at Cable
Replace cable
receiving end is
conductor
conductor.
not available.
between
Transmitting
end and
receiving end
is defective
Electrical Key Transmitter
(Rotary Type)
November 2001
CAMTECH/S/2001/EKT(R)/1.0
Sr Trouble
Supply is
available
R2 relay pickup
R2 relay contact
is proper
RKT spring
contacts are
proper
11.0
Do’s and Don’ts
11.1
Do’s
•
•
•
•
•
•
11.2
15
Cause
Remedy
R2 not pick up Check the
supply at relay
coil and
rectify
R2 front
Check front
contact giving contact
higher
resistance and
resistance
attend or
replace the
contact.
RKT spring
Open RKT
contact 2,3
check spring
and 4,5 are not contact and
making
adjust them.
properly
Coil may be
Check coil
break.
resistance with
multimeter if
defective
replace the
same RKT
coil.
Disconnect before Maintenance
Provide lightening dischargers in line circuit.
Check the insertion of wrong key.
Check the earth circuit if any is working properly.
Ensure sealing after maintenance.
Operational test should be done after providing cover with nut and bolt.
Don’ts
• Forget to check the LDs and buzzer.
• Allow the worn out brass tumbler.
• Allow earth resistance more than 10 Ohms.
• Forget to seal after maintenance.
• Do not replace AC immunised line relay with non immunised relay in AC
electrified area.
• Do not combine external and internal battery set.
„„„
Electrical Key Transmitter
(Rotary Type)
November 2001