General Description; Scanning Of Rotor Marks - ZERA TK326 Operation Manual

Scanning Head TK326 5

1. General description

The scanning head TK326 is developed to scan rotor marks and LED's of electronic meters.
If the TK326 is used to scan rotor marks, pulsed LED's light up the rotor disk. So the reflected
light is pulsed as well and can be detected independent of the background light. The scanning
heads TK326 can detect every single switching edge of a pulse and allows the automatic
starting- and no load-test on ZERA test systems.

2.1. Scanning of rotor marks

For the scanning of rotor marks place the scanning head in front of the meter disk in approx.
35 mm distance. The switch on the rear side must be in the upper position (opposite to „LED"
see chapter 2.3.2.). Place the rotor disk in the middle of the overlapping light spots as shown
in figure 1. The scanning head uses blue LED's to lighten the rotor mark having a much
stronger intensity than other available LED's and guarantee the best contrast to detect all
known black and red (even transparent) rotor marks.
mark light spots disk
Figure 1
The sensitivity of the scanning head is adjusted by means of the potentiometer on the rear by
observing the monitoring LED.
If this diode is lit and does not go out, while passing a mark, the potentiometer must be turned
anticlockwise until the diode goes out, while passing a mark. Pay attention that the monitoring
diode does not give double pulses. In this case turn the potentiometer a little bit clockwise.
TK326_MAN_EXT_GB_V102