TWR
TWR K10/0322 page 5
6. Use in Hazardous Areas
6.1. General
The temperature switches TWR-3 **** and TWR-4 **** can be used as follows
(taking into account the notes and the approved electrical limit values):
a) In zone 2 (Gas-Ex, EPL Gc) in explosion group IIA, IIB and IIC
b) In zone 22 (Dust Ex, EPL Dc) in explosion groups IIIA, IIIB and IIIC
c) In zone 1 (Gas-Ex, EPL Gb) in explosion group IIA, IIB and IIC, if the
temperature switch is operated via an intrinsically safe isolation amplifier
taking into account the defined characteristic data.
d) In zone 21 (Dust Ex, EPL Db) in explosion groups IIIA, IIIB and IIIC, if the
temperature switch is operated via an intrinsically safe isolating amplifier
taking into account the defined characteristic data.
The temperature switch also fulfills the requirements for a simple apparatus
according to EN 60079-14, section 12 and EN 60079-11, section 5.7.
6.2. Electrical Contact
The following limit values for the switching contact must not be exceeded:
Max. Switch capacity: Ui IIC = 30 V AC / DC
Ui IIB = 45 V AC / DC
Switching current: li IIC = 150 mA
li IIB = 250 mA
li IIIB = 250 mA
PiII = 1.2 W 40° C 550 mW @ 125° C
Li = negligible
Ci = negligible
The electrical connection is explained in section 8 Electrical Connection.
6.3. Equipotential Bonding
In order to achieve potential equilibrium, the temperature switch should be
properly grounded. This will occur only when the connection pipes are made of
metal.
