1, Relay Drive Output Operation
Both the AT5600, AT3600 and ATi transformer tester
possess a USER PORT connector (9-way, 'D' type, female).
This connector has been designed to facilitate an
open-collector relay drive output.
The relay drive output is provided in a unique test
Six relay drive outputs are available to the user and can be
pre-programmed via the Voltech AT Editor software to output to a number of
sources or applications.
Figure 1 below shows the pin-outs available for the six relay drives:
|| O/P user relay drive 0
|| O/P user relay drive 2
|| O/P user relay drive 4
|| +12V DC @ 1A
|| O/P user relay drive 1
|| O/P user relay drive 3
|| O/P user relay drive 5
Each relay output can drive a load of >150Ω and has a
maximum current output of 80mA.
An "OFF" state for the relay drive outputs is the default
setting when the AT is switched on.
However, after each programmed "OUT" test, the relay
drives will remain in the programmed condition until another "OUT" test is
run, or the AT is switched off and on again.
During subsequent "OUT" tests, the AT, firstly,
identifies relays that are programmed to be "OFF" and releases those
Secondly, the AT identifies relays that are programmed to
be "ON" and energizes those next.
The relay switching "OFF" time is almost instantaneous.
Switching "ON" times, however, are around 20mS.
2, Use Case - Component Switching
The most common use of the "OUT" test is to close a relay
in order to introduce an additional component to the test circuit, such as
a resistor, as shown in Figure 2.
Figure 3 shows a block diagram of the relay output, which is internal to
Component Switching Applications
The most common tests where the introduction of a component is required
are to measure impedance mismatch between the transformer and the
The component, in those cases, would be a resistor for tests such as GBAL
(General Longitudinal Balance), LBAL (Longitudinal Balance), ILOS
(Insertion Loss) and RLOS (Return Loss).
Discharging the circuit may be required where testing involves passive
components such as capacitors.
These may require discharging prior to operator removal of the part under
3, Use Case - Triggering for An External Device
During a test sequence, an external device may require triggering.
This could be either through a relay or direct to an "ENABLE" input by
using a pull-up resistor (Figure 4).
External Device Trigger Applications
- Batch counting. The trigger is sent to a digital or electrical counter
in order to count the entire batch being tested.
- Conveyor belt. The trigger is sent to a timer that operates a conveyor
belt, which moves passed parts along a production line.
- Robotic arm. The trigger is sent to a PC that controls a robotic arm
that removes tested parts and/or places parts that are ready for test.
4, Use Case - Test Cycle Indication
During a test sequence, an LED indicator (and/or buzzer)
can be used as an indication of a certain point within the program cycle
being reached (Figure 5).
Test Cycle Indication Applications
- A timed buzzer or illuminated LED to warn the operator that the part
is undergoing a hi-pot or high-voltage test.
- During multiple part testing (maximum of six - one LED per part
tested), an LED can be arranged to show the test status of a particular
part under test (i.e., LED illuminates when part is tested).
5, Relay Drive Set-up
The "OUT" test is accessed via the AT Editor software and
can be placed anywhere in a program cycle.
The AT Editor software allows an "OUT" test to be placed
anywhere in the program cycle.
Selection of the six relay drives is easy.
Simply click the left mouse button over the ON or OFF button on any of the
six drives required and click OK.
Activating a relay to add a component will require two
One to close the relay and introduce the component and another to open the
relay and remove the component once the test requiring this component has
Activating an enable output (and/or a program cycle
indicator) would require the "OUT" test set-up in the appropriate area of
the program in order to output the required event.
6, Typical Relay Specification And Recommended Cables
The list below shows the typical specification required
when using relays in circuit.
However, providing that a coil rating of >150Ω is used at 12VDC, other
relays (meeting the typical specification) can be used.
Typical Relay Specification
- Switching current: 2A maximum
- Coil resistance: 290Ω +/- 10%
- Reed switch isolation: 10KVDC
- Coil-to-contact isolation: 10KVDC
- Coil voltage: 12VDC
- Contact resistance: <50mΩ
- Voltech part number: 33-004
- Sub-miniature, screened 7/0.1 multi-core with minimum of seven cores
(Farnell part number: 711-380)