Instruction Manual

15 IOM-DPT-A: FEB 2014
5.4.5. Insulation Resistance
>100 MΩ @110V transmitters with gas arresters
>100 MΩ @750V DC transmitters without gas arresters (Exi)
5.4.6. High Voltage Test
500V AC, or 750V DC, 1min, transmitters without gas arresters (Ex applications)
75V AC, or 110V DC, 1min, transmitters with gas arresters
5.4.7. Enclosure ingress protection
EN 60529, IP 66,67
5.5. Construction materials
Electronics casing High pressure cast of aluminium alloy, lacquered with chemical-resistant oxide
enamel, colour yellow (RAL 1003), or stainless steel ss316L – not varnished.
Shields - materials, diameters and lengths.
Type of shield
Shield
Material of shield
Connection type
F [mm]
L [mm]
I [mm]
SW1
18h7
100
140, 200
35
65
15HM,
10H2M,
316Lss
-
SW2
24h7
140, 200
65
15HM,
10H2M,
316Lss
-
GB1, GN1
9 x 1
100, 160,
250, 400
-
316Lss
M20x1,5,
G1/2
G1
11 x 2
100, 160,
250, 400
-
316Lss
M27x2,
G1
T1
11 x 2
100, 160,
250, 400
-
316Lss
Flange PN, DIN, ANSI
6. CONSTRUCTION.
6.1. Measurement Principles.
A signal from measuring sensor, i.e. from thermometer resistor Pt100 or thermocouple, corresponding to
measured medium temperature, is delivered to the input of analogue-digital converter and converted to digital
form. In digital form it is sent, through an optoelectronic galvanic barrier, to the microcontroller. The
microcontroller reads measured values and, using built-in algorithms, calculates an exact value of temperature
on the basis of these algorithms. Calculated value is shown on integrated LCD display, which can be configured
depending on the needs (see p. 9.2.5). Digital value of measured temperature is converted to analogue signal
4...20[mA]. Built-in modem BELL202 and implemented communication stack HART Rev.5.1 allow for the
communication with the converter, using PC computer and appropriate software or communicator.
The transmitter’s output is fitted with a radio-noise filter and other elements protecting against ESD.
A block diagram of the transmitter is presented in Figure 1.
DPT ... converters monitors the operation of their measuring systems and the correctness of calculations and in
case when discrepancies occur they inform about an error displaying a message on LCD display and
generating an alarm current in the current loop (depending on configuration).
The measuring signal of sensor has a galvanic separation from measuring line. Thanks of that construction the
measurement susceptibility at interferences is reduced as well as the enlarged safety of work in the Ex and
flameproof applications.
6.2. Construction
The basic units of transmitter are: casing, shield with process connection, measuring sensor and electronic
units, transforming signal from measuring sensor into unified output signal.