Lamtec VMS Series, Руководство пользователя

Страница: 132 / 146

131
10 Appendix
Owing to the large number of usable transducers LAMTEC has only one two wire element and
one three wire element in it’s product range. It is selected in that way, that it covers a number
of measuring tasks. Other transducers only on enquiry or direct from the company Turck.
10.9.2 Selection of a Suitable R. P. M. Sensor
The correct sensor should always be selected, taking into account the structural features of
the element to be measured.
Since this element is not always known, the following is an approximation procedure for di-
mensioning the attenuating elements and selecting a suitable sensor.
In most cases, a shaft is sensed directly. One or several attenuating elements (screw-heads
or metal plates) are attached directly to the shaft. A symmetrical arrangement should be en-
sured, since many instruments work on the principle of measuring the period, and in the case
of more than one attenuating element require 100% equal intervals between them.
If this cannot be guaranteed, the signal can exhibit jumps (asymmetry can become particularly
noticeable in analogue signals). This problem can be solved by installing only one attenuating
element (this is the standard setting for rev. speed capture in the VMS).
Example of an attenuating element:
Usable NAMUR transmit-
ters: all Turck sensors, which contain Y0 or Y1 in their
type designation.
Item no. Description
660R8101 r.p.m. sensor as a two wire system
d = 12 mm, switch gab 2 mm
663R8103 inductive sensor with switch terminals in three wire system
d = 12 mm, switch gab 4 mm
Technical Data
Fig. 10-12 Attenuating element (example)