TF20 Datasheet - Applied Relay Testing

TF20 Datasheet - Applied Relay Testing
TF20 Wetting
The TF20 Wetting Module is designed to provide a nominal 24 Volt DC / 1
Amp contact load to assist the cleaning of contaminated electro-mechanical
relay contacts fitted with contacts with a minimum rating of 24 V/1A switching
capability. The module interfaces with the relay to be cleaned via a 60 pin
Hirose socket mounted at the front of the unit.
The action of operating and releasing relay contacts whilst applying a wetting
is primarily designed to assist the removal of contact contamination such as
oxidation or any other contamination, a secondary effect may be to open
welded contacts. Several operations of the TF20 test sequence may be
required to rectify the contact faults. However relay contacts which are
severely contaminated or welded might never recover and these should be
Relay compatibility
The unit is designed to be used with single coil mono-stable or dual coil bistable relays which can operate from a DC coil voltage not exceeding 250
Volts and have a maximum coil current not exceeding 0.5 Amps. Flashing and
timing relay types should not be used.
The unit is NOT suitable for use with relays which are fitted with one or more
gold plated or low power relay contacts. If used with this type of relay contact
the contact plating will be rapidly damaged.
Use with the TF10/TF15
The Hirose 60 pin connector is compatible with Applied Relay Testing’s
TF10/TF15 series test fixtures*. When connected, the ‘Test’ and ‘Retest’
switches will illuminate and pressing either the ‘Test’ or ‘Retest’ switch will
initiate a wetting sequence. Alternatively pressing the local TF20 ‘Start’ switch
will initiate a wetting sequence.
* These fixtures are custom designed for specific relay footprints – please
contact ART if alternate footprints are required.
Coil power selection
By default the rear panel slide switch should be set to ‘24V’. In this position
the unit will operate single coil mono-stable or dual coil latching relays
requiring a nominal 24 Volt dc coil voltage.
To use the unit with relays with other DC coil voltages the rear panel slide
switch should be set to ‘EXT’. In this mode coil power can be provided from
an external bench style power supply (not provided) connected to the rear
panel red (+ve) and black (-ve) 4mm terminals. Internal protection will disable
the coil power should the polarity of the external power supply be reversed.
Relays which require an AC only coil drive are not suitable for use with this
Contact status LEDs
During the wetting sequence, the top panel indicates the status of the relay
contacts an up to 4 change over contacts. An LED illuminates when the
associated device contact is closed. At the end of the contact wetting
sequence the LEDs will all extinguish regardless of the relay contact state.
Powering up the TF20
The unit is powered from an external mains operated 24V dc power supply.
The inlet to this power supply uses a figure of 8 power lead (supplied) which
should be connected to a mains socket using a plug fitted with a 3A fuse. The
outlet power connector of this supply should be connected to the TF20 rear
panel 2.1mm power inlet (centre positive).
The power supply provides the power to the contact loads, system control
circuitry and optionally the device coil(s). Internal protection will disable the
power supply should the polarity of the external power supply be reversed. If
the power supply is replaced then a substitute 24V/5A DC supply may be
The TF20 power can then be enabled using the rear top panel ‘Power’ rocker
switch, the accompanying green power LED will illuminate and the internal
cooling fan will operate.
Caution: To avoid damage to the unit or PSU do not obstruct the vents whilst
power is applied.
Test sequence
Momentarily press the ‘Start’ or TF10/15 ‘Test’ or ‘Retest’ switch to
commence the wetting sequence. Any further presses of one or more of these
switches will be ignored until the sequence finishes at which time the status of
the switches will once again be monitored.
The unit applies the wetting load to the closed contacts of the relay under test.
A burst of 20 coil operating pulses will be applied alternatively to the SET and
RESET coil (if fitted) in such a way that either single coil mono-stable or dual
coil latching relays can by cycled automatically.
The top panel yellow LEDs monitor up to four Normally Open (NO) and four
Normally Closed (NC) contacts. During the test sequence contact status LEDs
will indicate if contact load current is flowing in the relay under test.
An LED which is permanently enabled indicates:
a contact weld
damaged relay coil
insufficient coil voltage
relay coil cannot be operated from a DC coil power supply.
An LED which is permanently disabled indicates:
the contact is still contaminated
the device under test does not have a contact in that position
damaged relay coil
insufficient coil voltage
relay coil cannot be operated from a DC coil power supply.
If required the wetting process can be repeated as required to see if the relay
contact begins to operate correctly.
After 20 device cycles the unit will remove power from the device coils and
contact loads. The fan continues to operate until the power switch is turned off
to allow any internal heat built up in the contact load resistors to be dissipated.
Whilst the wetting load is being applied the fan in the external power supply
may also operate.
Connector pin assignments
Power inlet
External coil interface
RUT = Relay Under Test
215 x 143 x 70 mm
Operating Temperature
5 to 40 °C
BS4800 00A05 powder coated
BS4800 00A01 powder coated
Coil select switch
24Vdc to RUT coil(s)
External DC supply to RUT
External coil input
4mm terminals,
red +ve, black –ve
250Vdc max
0.5A max
Duty cycle
24Vdc +/-10%
1Adc +/-10%
20 +/- 1
50%/50% bi-stable relays
45%/55% mono-stable relays
RUT specification
Coil type
Max 4PCO
Single coil mono-stable or
Dual coil latching
250V dc max
0-0.5A dc
Coil voltage
Coil current
External Power supply:
Output connector
Input connector
170 x 60 x 35 mm
24V dc, 5A
2.1mm, Centre positive
Figure 8
Note: In the interest of continuous product improvement, ART may change
these specifications without prior notice.
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