Page 945 - Sensors and Systems - North American Catalog
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Logic Control Units
9
943
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Logic Control Units
Introduction
Operation
The requirements for an optimal operational philosophy differ
depending on the application. These requirements are as follows:
•
No preset function or just a reset function
•
Very easy and clear operation with limited functionality
•
Menu-driven operation with a high level of flexibility for the application.
•
These requirements are fulfilled in this order by the series:
•
KCM (no adjustment option)
•
KCY (simple adjustment of preset values using one button per digit)
•
KC-L and KCT (menu-driven operation and connection via
RS232‑interface, keylock can be activated).
9.2 Tachometers
Tachometers are pulse-controlled time measurement devices.
In contrast to standard tachometers (KCT Series) that count the
incoming pulses within a gate time, TC-type tachometers evaluate
the duration of a period between two subsequent input pulses
(cycle method).
The period duration is allocated an adjustable multiplication factor
and is converted into a rotational speed or speed depending on the
operating mode.
Benefit
The cycle method requires only one pulse per revolution and a
maximum of two revolutions to detect the rotational speed with high
accuracy.
Rotational speed = 1/T x 60 min
-1
T = time between two pulses
min-1 = revolutions/minute
9.3 Sensor Output Adapters
Sensor output converters form the interface between the sensor and
thesystemcontroller or actuator if theoutput signal of thesensor cannot
be used directly. Sensor output converters are useful for connecting
three-wire sensors. If the current load for the sensor-specific output
stage is insufficient for the connected load, or if a semiconductor
output needs to be converted to a relay contact output.
9.4 Rotation Speed Monitors
Rotation speed monitors display and monitor periodic signals, i.e.,
pulse frequencies which represent some rotational speed. These
periodic signals occur in almost all areas of automation and process
technology.
The input signals are evaluated depending on the cycle method,
i.e., through period duration measurement, and are converted into
frequency or rotational speed.
Particular attention was paid to rotation speed monitoring during the
development of these devices. Displays and data can be provided
in either Hz or 1/min.
The monitoring function operates using a trip value for which the
upper and lower hysteresis value can be freely selected within the
respective measurement and display range. The output signal is
generated when the predefined limits are exceeded or not met.
In addition to the ON delay and OFF delay, pulse function, and OFF
delay timer, it is possible to select the direction of operation for the
output, i.e., for underspeed or overspeed monitoring. A built-in start-
up override prevents false signals during start-up of the monitored
system.
All common two-, three-, or four-wire proximity sensors and
incremental rotary encoders can be used as signal sources.
Terminals are also available for connecting proximity switches in
accordance with DIN 19 234 (NAMUR).
9.5 Frequency Voltage Current Converters
Frequency voltage current converters function in the same way as
rotation speed monitors. The difference is that a voltage or current
value that is proportional to the input frequency is generated as the
output signal:
•
0 V ... 10 V
•
2 V ... 10 V
•
0 mA ... 20 mA
•
4 mA ... 20 mA
A pulse output is available as a function of the input frequency
divided by an adjustable factor (1 to 1200).
