Vaisala HMT370EX - Probe Options; HMT370 EX Probe Options Overview

Wiring requirements
• The cable glands and cables used for wiring the device must not impair the Ex protection.
• Unused lead-throughs must be sealed using Ex compliant plugs.
• Select a strain relief option that suits the application (either use cable glands that include
strain relief or install separate clamps: see IEC 60079-14).
Connect only de-energized wires. Never switch on the power supply
input before completing the wiring and closing the transmitter body.
CAUTION!
Intrinsic safety
The overvoltage category of HMT370EX transmitters is I (non-mains equipment), and ambient
pollution degree is 4, as specified in IEC 60664-1. For intrinsically safe input parameters, see
Table 28 (page 59).
Table 28 Intrinsically safe input parameters
Parameter Value Associated apparatus entity
parameters
U
i
28 VDC U
o
≤ U
i
I
i
100 mA I
o
≤ I
i
P
i
700 mW P
o
≤ P
i
C
i
12.1 nF C
o
≥ C
i
+ C
cable
L
i
16 µH L
o
≥ L
i
+ L
cable
Using analog output test points
There are test points for measuring the voltages and currents of the analog outputs, located
above each screw terminal block as shown in Figure 19 (page 60). Accessing the test points
on the component board requires opening the transmitter enclosure.
Chapter 3 – HMT370EX regional safety certification information
59