82
8024250/18HT/V2-0/2020-12| SICK
O P E R A T I N G I N S T R U C T I O N S | ZIRKOR200 Ex-G
Subject to change without notice
10
HEATING SHUTDOWN IN CASE OF MALFUNCTION
10.2
Functional description
The fail-safe heating shutdown can be used to switch the heating off when the limit
temperature of heaters is exceeded, especially for ATEX-certified O
2
analyzer units.
The heating shutdown is permanently set to the temperature specified in the order code
(standard is 810 °C).
The temperature is measured by means of two type K thermocouples housed in a sheathed
thermoelement. The device has two independent channels. Each of these channels
switches a relay when the specified maximum temperature is reached.
The contacts of both relays are connected in series so that the heating is switched off when
the temperature in one channel is exceeded. The heating is also switched off when the
supply voltage is lost. Furthermore, the difference between the two channels is monitored;
the heating is switched off when the difference is more than 32 °C.
10.3
Maintenance
The heating monitoring is checked by the manufacturer before delivery.
The heating monitoring device must be returned to SICK for inspection at the latest by the
date noted on the calibration label (
see “Display and operating elements”, page 81
