Delta Controls DPR-2000 - Manual (Page 21)

A 19 IOM-DPCDPR-A: FEB 2014
9.3.2. In order to protect against excess voltage between the transmission line and the casing or earth (not
prevented by the diodes connected between the transmission wires), additional protection is provided in the
form of plasma surge arresters (see the table, column 3).
Also external protective devices may be used, e.g. the UZ-2 Delta Controls system, or others. When the
transmission lines are long, it is advantageous to use one protective device near the transmitter (or inside it), and
another near entry points to other devices used in conjunction with it.
Internal protection of transmitters:
1 2 3
Type of
transmitter
Protection between wires (TVS
diodes) – permitted voltage
Protection between wires and earth and/or casing –
type of protection, permitted voltage
DPC...,
DPR...
68V DC
(39V DC for Exi version)
Plasma surge arresters - 230V DC
(Not applicable to Exd version).
9.3.3. The voltage in the protective elements must not exceed the maximum permitted values given in columns
2 and 3 of the table.
The insulation test voltages (500V AC or 750V DC) given in 5.1.1 refer to transmitters plasma surge
arresters - such protection is not used in Exi versions of transmitters.
9.4. Earthing
The transmitters are fitted with internal and external earth terminals.
10. SETTING AND REGULATION
DPC..., DPR... transmitters are factory calibrated to the range stated in the order or to the basic range.
After installation, the transmitter’s zero-point may move and require adjustment.
This applies particularly in cases where the measurement range is small, where the impulse lines are filled with
a separating liquid or where DPC..., DPR... transmitters are used with remote diaphragm seals.
10.1. Transmitter Range,Basic Range. Definitions
10.1.1. The maximum range of pressure, or differential pressure, which the transmitter can measure is called
the
“basic range” (for specifications of basic ranges see section 5.2.1, 5.3.1, 5.3.2, 5.4.1, 5.5.1).
The width of the basic range is the difference between the upper and lower limits of the basic range.
The internal characteristic conversion curve for the basic range is coded in the transmitter’s memory.
This is the reference curve used when making any adjustments which affect the transmitter’s output signal.
10.1.2. When the transmitter is in use the term “set range” is used. The set range is the range whose lower
end-point corresponds to an output current of 4mA and whose upper end-point corresponds to a current of
20mA (or 20mA and 4mA respectively when the conversion curve is inverted).
The set range may cover the whole of the basic range or only a part of it.
The width of the set range is the difference between its upper and lower end-points.
The transmitter may be set to any range within the basic range of pressure values, subject to the restrictions set
out in the table in section 5.2.1, 5.3.1, 5.3.2, 5.4.1, and 5.5.1.
10.2. Configuration and Calibration
10.2.1. The transmitter has features which enable metrological and identification parameters to be set and
altered. The configurable metrological parameters affecting the transmitter’s output current include the
following:
a) unit in which the measured pressure is expressed on the display
b) upper end-point of the set range
c) lower end-point of the set range
d) time constant
e) type of characteristic curve: linear or radical
Parameters of an informational nature which cannot be altered include the following:
f) upper limit of the basic range
g) lower limit of the basic range
h) minimum range
i