Basler Electric BE1-59NC - Manual (Page 20)

The definite time delay is adjustable from 00.1 to 99.9 seconds in 0.1 second increments. Front panel
mounted switches determine the delay. Position 00.0 is instantaneous.
Inverse Time Delay
Inverse time delay circuits are identical to definite time delay circuits except that a voltage controlled
oscillator (VCO) is substituted for the clock signal. The VCO is controlled by a voltage derived from the
sensed input. Because the frequency of the oscillator is kept proportional to the sensed input voltage, the
desired inverse time delay is produced.
Inverse time characteristic curve thumbwheel switches are settable from 01 to 99 in 01 increments. Each
position corresponds to a specific curve setting except 00, which is instantaneous. Refer to Figures 1-3
and 1-4 to see the inverse time characteristic curves.
Reference Voltage Circuit
A constant voltage source provides a reference voltage to the potentiometers on the front panel. The
potentiometers, in turn, provide reference voltages to all the comparator circuits and establish the
threshold for each circuit.
Power Supply Status Output
The power supply status relay has a set of normally closed contacts and energizes when operating power
is applied to the relay. If relay operating power is lost or either side of the power supply output (+12 Vdc
or –12 Vdc) fails, the power supply status relay de-energizes and closes the power supply status output
contacts.
Power Supply
Operating power for the relay circuitry is supplied by a wide range, electrically isolated, low-burden power
supply. Power supply operating power is not polarity sensitive. The front panel power LED and power
supply status output indicate when the power supply is operating. Power supply specifications are listed in
Table 1-1.
Target Indicators
Target indicators are optional components selected when a relay is ordered. The electronically latched
and reset targets consist of red LED indicators located on the relay front panel. Latched targets are reset
by operating the target reset switch on the front panel. If relay operating power is lost, any illuminated
(latched) targets are extinguished. When relay operating power is restored, the previously latched targets
are restored to their latched state.
A relay can be equipped with either internally operated targets or current operated targets.
Internally Operated Targets
The relay trip outputs are directly applied to drive the target indicators. The indicators are illuminated
regardless of the current level in the trip circuits.
Current Operated Targets
Current operated targets are triggered by closure of the corresponding output contact and the presence of
at least 200 milliamperes of current flowing in the trip circuit.
NOTE
Prior to September 2007, the BE1-59NC target indicators consisted of
magnetically latched, disc indicators. These mechanically latched target
indicators have been replaced by the electronically latched LED targets in use
today.
3-2 BE1-59NC Functional Description 9279400990 Rev F