automatically compensate for an input voltage deviation of 10 percent. If the input voltage is
outside this tolerance, contact the local power company and have it corrected. If this is not
practical, autotransformers may be used to adjust the input voltage.
2. If the input voltage is present but it is not within the range of the tap or
tap-selector switch (when used), connect the regulator to a suitable source of power by using the
required distribution transformers or use a regulator with an input rating suitable for this input
3. If the input voltage is present and corresponds with the setting of the taps
or tap-selector switch, then the regulator is not operating satisfactorily and the fault is in the
brightness controls, in the regulator, or in the load circuit.
(4) If the input voltage is zero, continue moving the potential transformer and/or
the voltmeter toward the source of power and repeating the voltage measurements until the fault
is located. Note that the circuit must be de-energized every time the meter is moved.
(a) When the point of failure of the input voltage is located, make the repairs.
(b) If the incoming power lines are dead and cannot be restored by facility
personnel, notify the power company or other local authority.
(5) Inspect the operation of the brightness relays in the regulator.
(a) Check the wiring in the brightness control circuitry for loose wires,
shorting, or other damage.
(b) Check the condition of the points on the brightness relays, and recondition
or replace as necessary.
(c) If the regulator does not change brightness steps properly when remotely
controlled, the problem may be inductance between remote control lines.
(6) If the remote-energizing controls operate satisfactorily, check the continuity of
the regulator secondary with an ohmmeter. Be sure the input power is disabled, either by
opening a switch or removing the lines, then remove the output cables and measure the resistance
across the output terminals.