TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas

Page 62
11. Operational Check for Selectors on Reduced Voltage. (See Fig. 24.)
Testing Selectors No. 4301 or 4304 on Reduced Voltage.
In order to ascertain whether a selector will operate correctly on a voltage
less than the full line battery, the following tests can be carried out :
(a) If a Selector only is to be tested, it should be connected to Terminals
Test 1 and 2.
(b) If a Selector complete in the Selector Set is to be tested, Ll and L2
terminals of the set should be connected to Test Set Terminals Test 1
and 3.
Reduced Voltage Test for 4301-A and 4304-A Selector
Fig. 24.
(c) A selector at a station can be tested if someone is there to observe its
operation.
In the case of (a) and (b), a spare Selective circuit should be used if
available, or if a working circuit has to be used the key LCO should be used
to cut off the line. In the case of (c), key LCO should not of course, be
operated. Operate key RVA and adjust potentiometer to the fraction of the
voltage required. Then transmit the code of the Selector under test.
Repeat the test with key RVB operated, which will show whether the
selector is free from bias, since it reverses the polarity of the impulses.
A good selector should operate down to 80 volts when connected
direct to the Test Set, and down to 0.7 of the normal line voltage when
tested with the line wires in circuit.