1. * GB780068 (A)
Description: GB780068 (A) ? 1957-07-31
Apparatus for measuring the time of energisation and de-energisation of
electric relays
Description of GB780068 (A)
COMPLETE SPECIFICATION Apparatus for Measuring the Time of
Energisation and
De-Energisation of Electric Relays We, TESLA, N#RODN# PODNIK, of 186,
Podebradska, Praha-Hloubetin, Czechoslo
vakia, a Czechoslovak National Corporation,
do hereby declare the invention for which we pray that a patent may be
granted to us, and
the method by which it is to be performed to
be particularly described in and by the follow- ing statement:
This invention relates to an apparatus for measuring the time of
energisation and deenergisation of electric relays with make or
break contacts.
The terms "time of energisation" and "time
of de-energisation" relate to the time beginning with the moment when
the energising circuit of the relay under test is closed or
opened and ending with the moment when the
contact is closed or opened as a result of the energisation or
de-energisation.
Due to production tolerances, these times
are different even with relays of the same production series, and
their adjustment to the
correct value is carried out after assemblage.
A measuring apparatus is therefore required which oan measure times
ranging from several tenths of microseconds to several seconds.
Readings should be possible immediately after the measurement or after
some time, and it should be possible to quickly repeat the
measurement. It should also be possible to measure the functional
dependence of the time of energisation or de-energisation, for example
on the resistance of the relay. It is also desir- able that the

2. apparatus has a linear scale.
Measuring apparatus for the above mentioned purpose meet only some of
the stated requirements; they have, moreover, various drawbacks.
Some known apparatus use a suitably cone nected measuring capacitor.
The measurement is accomplished either by comparing the charge of this
capacitor with the charge of another capacitor having a known rate of
charging, or by measuring the time of charging or discharging.
Accurate measurement, particularly of short periods, requires the
simultaneous closing or opening of the energising circuit of the relay
and of the charging or discharging circuit of the measuring capacitor.
In order to meet this requirement at least approximately, a mechanical
twin contact has been used, one contact controlling the energising
circuit of the measured relay, and the other contact @@@trolli@@ @@
the other contact controlling the circuit of the measuring capacitor.
The action of this twin contact is not perfectly synchronous, and the
measurement is therefor not accurate.
In accordance with the invention, the apparatus for measuring the time
of energisation and de-energisation of electric relays with make or
break contacts, comprises a grid controlled charging valve which has
in its anode circuit a capacitor the charge of which is used as a
measure of the time during which the charging valve is made
conductive, and a control circuit for starting and stopping the
current passing through the charging valve so that the current is
allowed to pass through this valve only during the interval required
for the energisation or de-energisation of the relay, which control
circuit includes two control valves a first v@lv@ @@@ valves, a first
valve and a second valve, so connected that the anodes of both valves
are connected to a source of anode potential through a common parallel
connection of a switch and two temrinals which serve for the
connection of the contacts of the relay under test, that both anodes
are adapted to be alternatively connected through a change-over switch
to the control grid of the said charging valve, that the anode of the
first control valve is also connected to the control grid of the
second control valve, that the control grid of the first valve is
connected through a switch to the earthed cathode and is adapted to be
connected to a negative potential through terminals for the connection
of the coil of the relay under test and @@@ @@@
elay under test, and that the control grid of the charging valve is
also adapted to be connected to earth through terminals for the con-
nection of the contacts of the relax under test.
In order that the invention ma- le clearly understood, a preferred
embodiment thereof will now be described by way of example with
reference to the accompanying drawing.
The apparatus shown comprises three vaives 4, 5 and 6, the first two

3. being referred to as control valves, and the third as a charging
valve. The first control valve 4 is a pentode and the second 5 is a
triode. Their anodes are connected with the control grid of the
charging valve 6 through corresponding contacts 42 or 43 of a switch
15. and a grid resistor 27 of the charging valve. Therefore, in each
position of switch 15 the petentia; of the anode cf one of the control
valves 4 or 5 controls the function of the charging valve 6 the anode
of which is connected to a source of positive potential. Inserted in
this anode circuit is capacitor 23. The charge of this capacitor is
measured by valve voltmeter 26, not shown, connected at points 24 and
25 across the capacitor 23. The anode of valve 4 is connected with the
control grid of valve 5 through a resistor 28. The energising winding
of the measured relay 3 is connected between terminals 1 and 2 in the
grid circuit of the control valve 4. The make and break contacts 30,
31 respectively of the measure relay 3 can be connected, in accordance
with the nature of the measurement, either between the terminals 17
and 18 in the grid circuit of the charging valve 6. or between the
points 19 and 20 in the anode circuit of the control valves 4 and 5,
as will be described hereinafter. The onera- tional voltages for the
valves and the exciting current for the winding c-f the ineaslared
relay are obtained from the resistive voltage divider 7 to 12,
grounded at the point 36 between the resistors 11 and 12. The screen
grid of the charging valve 6 is connected to point 32 between the
resistors 7 and 8, and its cathode is connected to the point 33
between the resistors 8 and 9. The screen grid of the control valve 4
is connected to the noint 34 between the resistors 9 and 10, and its
cathode is grounded at the point 36. The cathode of the control valve
5 is connected to the point 35 between the resistors 10 and 11. The
anode voltage for the two control valves is supplied from the point 32
through a press button switch 16 when the latter is closed, or by the
closed relay contacts when the latter are connected to the terminals
19 and 20, and through the respective resistors 13 and 14 which are
much higher than the internal resistances of the valves 4 and 5.
If the time of energisation of a relay 3 with a make contact is to be
measured, the normally open contact pieces 21 and 22 of the make
contact 30 are connected to the terminals 17 and 18, the switch 15 is
moved to position 43, and the press-button switch 16 is closed. The
anode voltage of valve 5 reaches the control grid of the charging
valve 6 through the switch 15 in posftioii 43 and through the resistor
27, and blocks the charging valve 6. The energising winding of relay 3
is connected between the terminals 1 and 2 while the measuring switch
29 is opcn, so that the control grid of valve 4 is connected to the
negative pole of tile voltage divider 7 to 12 at the point 37.
The valve 4 is thus blocked, the valve 5 is caiductive and the valve 6

4. remains blocked.
As socn as the measuring switch 29 is dosed, the control grid of valve
4 is connected with its cathode, and this valve becomes conductive.
This blocks valve 5 whose anode becomes more positive and makes the
charging valve 6 conductive whereby the charging of the measuring
cal-acitcr 23 begins. At the same time, the energising circuit of
relay 3 has been closed, and the energisation of the relay h gins.
After the interval required for the energisation of the relay, the
contact pieces 21 and 22 of the make contact 30 close, so that cie
control grid of the charging valve 6 is connected to the ground
potential at point 36, and the valve is blocked, with the result that
the charging of the measuring capacitor 23 ceases.
The valve 6 is d pentod;e so that it passes a substantially constant
current, independent of the voltage across the capacitor 23. The
magnitude of the current of the charging valve 6 is controlled by the
voltage of its screen grid. The voltage across the measuring capacitor
23 is directly proportional to time and the anode current of the
charging valve. The measuring range cf the apparatus can be directly
increased or reduced by changing the voltage of the screen grid
thereby obtaining a resulting change in the anode current. The time
required to obtain a certain charge on the capacitor anc a certain
deflection on the valve voltmeter 26, is given by the equation
it e= , following from the equation
C
<img class="EMIRef" id="026474202-00020001" />
tilt. Fer a corstant pentode current and a constant capacity of the
measuring capacitor, the @oltage of the capacitor and the deflection
on the voltmeter is directly proportional to time. Therefore, the
scale is linear.
The decrease in the anode current with a change in the voltage of the
pentode is negigible, because the error caused through this decrease
is considerably smaller than the measuring error of the valve
voltrneter.
Similarly it is possible to measure the time of energisation of a
relay with a breaking contact 31. In this case the closed contact
pieces 38 and 39 are connected between the terminals 19 and 20, while
the relay 3 is deenergised. The press-button switch 16 is opea
The switch 15 remains in position 43. If the energising winding of the
relay 3 is connected between the terminals 1 and 2 and the ineasur-
ing switch 29 is closed, similar conditions prevail as described in
the previous case. The measuring capacitor 23 is charged until the
moment when the energiset relay opens the contact 31 whereby the
anodes of the valves 4 and 5 are disconnected from their anode
voltage. Due to the thermionic emission from the heated cathode of the

5. valve 5, the anode there of becomes sufficiently negative to block the
charging valve 6 so that the charging of the capacitor 23 ceases.
Then measuring the time of de-energisation of a relay with a make
contact, contact pieces 21 and 22 of the make contact 30 are coils
nected to the terminals 19 and 2U. The switch 15 to now moved to
position 42 and the pressbutton switch 16 is open. After connecting
the energising winding of relay 3 between tne terminals 1 and 2, the
relay 3 is energised by closing the measuring switch 29, so that the
contact 30 closes after a certain time. The valve 4, whose control
grid is now connected with its cathode, passes current and its anode
supplies through the switch 15 in the position 42 and the grid
resistor 27 a biasing potential to the control grid of the charging
valve 6, so that this valve is blocked.
Switch 29 is now opened, breaking thereby the energising circuit of
the relay 3 thus starting its de-energisation. At the same time, the
control grid of valve 4 is connected to the negative pole of the
voltage divider 7 to 12 at the point 37, blocking this valve. Through
the closed contacts 21, 22, the resistor 13 and the grid resistor 27,
the voltage from the point 32 reaches the control grid of the charging
valve 6 which becomes conductive and begins to charge the measuring
capacitor 23. As soon as the relay is de-energised, the contact 30
opens, interrupting the connection between the point 32 and the
control grid of the valve 6. The anode of valve 4 is disconnected from
the source of anode voltage, and due to continuing thermionic emission
from the heaved cathode, the anode becomes negative, and its negative
potential again blocks the charging valve, thereby terminating the
charging of the measuring capacitor.
The time of de-energisation of a relay with a break contact is
measured by connecting the contact pieces 38 and 39 of the break
contact 31 between the terminals 17 and 18. The press-button switch 16
is closed. The switch 15 is in position 42. If the relay 3 is
de-energibed. the contact 31 is closed across the terminals 17, 18 so
that the control grid of the charging valve 6 is connected to ground
through the grid resistor 27 and the valve is blocked. By closing the
measuring switch 29, the valve 4 becomes conductive, as described
above, and supplies to the charging valve 6 a blocking potential. As
soon as the relay 3 becomes energised, the contact 31 opens. Now the
measuring switch 29 is opened so that deenergisation of the relay
begins. Valve 4 ceases to pass current, and the positive potential of
point 32 is applied via the closed press-button switch 16, the
resistor 13, the switch 15 in position 42 and the grid resistor 27, to
the control grid of valve 6 causing it tol conduct so that the
charging of the measuring capacitor 23 begins. As soon as the relay is
de-energised, the contact 31 is again closed, the control grid of the

6. charging valve 6 is grounded and this valve is again blocked, so that
the charging of the capacitor ceases.
What we claim is:
1. An apparatus for measuring the time of energisation or
de-energisation of electric relays with make or break contacts,
comprising a grid controlled charging valve which has in its anode
circuit a capacitor the charge of which is used as a measure of the
time during which the charging valve is made conductive, and a control
circuit for starting and stopping the current passing through the
charging valve so that current is allowed to pass through this valve
only during the interval required for the energisation or de-energisa-
tion of the relay, which control circuit includes two control valves,
a first valve and a second valve, so connected that the anodes of both
valves are connected to a source of anode potential through a common
parallel connection of a switch and two terminals which serve for the
connection of the contacts of the relay under test, that both anodes
are affiapted to be alternatively connected through a change-over
switch to the control grid of the said charging valve, that the anode
of the first control valve is also connected to the control grid of
the second control valve, that the control grid of the first valve is
connected through a switch to its earthed cathode and is adapted to be
connected to a negative potential through terminals for the connection
of the coil of the relay under test, and that the control grid of the
charging valve is also adapted to be connected to earth through
terminals for the connection of the contacts of the relay under test.
2. An apparatus according to Claim 1, wherein the charging valve is a
pentode.
3. An apparatus for measuring the time of energisation and
deeergisation of electric relays with make and break contacts subst.n-
tially as described with reference to, and as illustrated irb the
accompanying drawing.