WIKA TR25 - Handbuch (Seite 21)

WIKA operating instructions model TR25 (Ex i)
14073045.01 10/2013 GB/D
21
GB
8. Electrical connection values
8.1 Electrical data without built-in transmitter or digital display
For group II instruments (potentially explosive gas atmospheres) *3 , t he following maximum
connection values apply:
U
i
= DC 30 V
I
i
= 550 mA
P
i
(at the sensor *1 ) = 1.5 W
For Group II instruments (potentially explosive dust atmospheres), the following maximum
connection values apply:
U
i
= DC 30 V
I
i
= 550 mA
P
i
(at the sensor *2 ) = for the values, see „Table 2“ (column 2), chapter 7.1.2 “Ex marking”
*1 The permissible power to the sensor depends on the temperature of the medium TM, the temperature class
and the thermal resistance Rth, but shall not be more than 1.5 W.
For calculation examples, see chapter 9 “Calculation examples for self-heating of the tubular body at the
sensor installation point”.
*2 The permissible power to the sensor depends on the temperature of the medium T
M
, the maximum allowed
surface temperature and the thermal resistance R
th
, but shall not be more than the values from „Table 2“
(column 2), see chapter 7.1.2 “Ex marking”.
*3 Use in methane atmospheres
Owing to the higher minimum ignition energy of methane, the instruments can also be used where methane
causes a potentially explosive atmosphere. The instrument can be optionally marked with IIC + CH
4
.
The internal inductance (L
i
) and capacitance (C
i
) of the TR25 are negligible.
Sensor circuit in Ex ia or ib, IIC intrinsic safety ignition protection
Only for connection to intrinsically safe circuits with the following maximum output values for
Group II instruments (potentially explosive gas atmospheres):
U
o
= DC 30 V
I
o
= 550 mA
P
o
= 1.5 W
For Group II instruments (potentially explosive dust atmospheres), the following maximum output
values apply to their connection to intrinsically safe circuits:
U
o
= DC 30 V
I
o
= 550 mA
P
o
= for the values, see „Table 2“ (column 2), chapter 7.1.2 “Ex marking”
8.2 Electrical data for built-in transmitters or digital displays
For the sensor circuit, the values mentioned in 8.1 apply.
Signal circuit in Ex ia or ib, IIC intrinsic safety ignition protection
U
i
= depending on the transmitter/digital display
I
i
= depending on the transmitter/digital display
8. Electrical connection values