Dwyer PMT2 Serie Manual Del Usuario página 3

WIRING
NOTICE • Always install or service this device with the power off and where
required install a disconnect lockout
• Use 16 to 20 AWG copper wire only for line and load connections. Installation must
be made in accordance with local codes and regulations such as the National Electric
Code
• Degree of protection TYPE 4 (IP66) is maintained when suitable glands/plugs are
used in conjunction with UL Listed models
HAZARDOUS LOCATIONS
WARNING
To prevent ignition of hazardous locations the following cau-
tions should be taken:
• Keep device covers tightly closed in operation
• De-energize supply circuit before opening device covers
• Replace device covers before energizing the electrical circuits
• Device is not field repairable and should be returned to Dwyer Instruments if repair
is needed
INTRINSIC SAFETY SPECIFIC CONDITIONS OF USE
WARNING
To maintain Intrinsic Safety the following cautions should be
taken:
• 4-20 mA signal and remote zero must be treated as separate circuits
• Enclosure parts are constructed of aluminum. Enclosure must be protected from
ignition hazard due to impact or friction
• All openings to enclosure must be sealed using suitable glands and/or plug main-
taining a minimum IP rating of IP66 for UL Listed models and IP65 for ATEX/IECEx
compliant models
• Substitution of parts may impair Intrinsic Safety.
CONTROL DRAWING UL LISTED INTRINSIC SAFETY (SUFFIX U2):
UL Listed Intrinsically Safe for use in Class I Div. 1 Groups C and D; Class II Div. 1
Groups E, F and G; Class III Div. 1; Class I Zone 0 AEx ia IIB T4 Ga; Class I Zone 0 Ex
ia IIB T4 Ga; T4@63°C when installed in accordance with Control Drawing 001744-48
on page 6 of this document.
ATEX COMPLIANT (SUFFIX A2)
II 1 G Ex ia IIB T4 Ga (-40°C ≤ Tamb ≤ 63°C) (-40°C ≤ T
IIIC T120°C Da (-40°C ≤ Tamb ≤ 63°C) (-40°C ≤ T
accordance with Control Drawing 001744-81 on page 7 of this document.
IECEx COMPLIANT (SUFFIX A2)
Ex ia IIB T4 Ga (-40°C ≤ Tamb ≤ 63°C) (-40°C ≤ T
Da (-40°C ≤ Tamb ≤ 63°C) (-40°C ≤ T
with Control Drawing 001744-81 on page 7 of this document.
INTRINSIC SAFETY INPUT PARAMETERS:
4-20 mA Signal, Vmax (Ui) = 28 V; Imax (li) = 93 mA; Ci = .022 μF; Li = 0.373 mH;
Pmax (Pi) = 651 mW
Remote Zero, Vmax (Ui) = 28 V; Imax (li) = 93 mA; Ci = Negligible; Li = 0 mH; Pmax
(Pi) = 651 mW
4
4-20 mA
3
2
REMOTE ZERO
1
Figure 1: General Installation Wiring (Non-IS)
≤ 120°C) / II 1 D Ex ia
Process
≤ 120°C) when installed in
Process
≤ 120°C) / Ex ia IIIC T120°C
Process
≤ 120°C) when installed in accordance
Process
POWER
SUPPLY
RECEIVER
REMOTE ZERO SWITCH
(IF USED)
POWER SUPPLY REQUIREMENTS
The maximum DC power supply is 28 VDC. The minimum required DC power supply
is based upon the following:
1. Minimum DC voltage requirement of the Model PMT2.
2. Total load resistance.
3. Total leadwire resistance.
4. Zener barrier voltage drop (Model PMT2-XX-X-X2 only).
The formula for calculating the DC Power Supply is:
VDC = VPMT2 + VLOAD + VLEADWIRE + VBARRIER
Where VPMT2 = 9.5 V
VLOAD = Total load resistance X 20 mA
VLEADWIRE = Total leadwire resistance X 20 mA
VBARRIER = 8.1 V (Typical zener barrier voltage drop for this application)
Example 1: Calculate minimum DC power supply for intrinsically safe models
Step 1 VPMT2 = 9.5 V
Step 2 Calculate VLOAD. Using the industry standard 250 Ω conversion
resistor, VLOAD = 250 X 20 mA = 5 V.
Step 3 Calculate VLEADWIRE. For this example assume a leadwire
resistance of 10 Ω, VLEADWIRE = 10 X 20 mA = 0.2 V
Step 4 VBARRIER = 8.1 V
Step 5 VDC = VPMT2 + VLOAD + VLEADWIRE + VBARRIER = 9.5 + 5 +
0.2 + 8.1 = 22.8 V
CONTROLS
LIVE MAINTENANCE PROCEDURE
WARNING
Live maintenance of Zero, Averaging Time, Range and Test
controls cannot be performed when a flammable or combustible atmosphere is
present.
Zero Switch (see Figure 2)
Press and hold the switch for 3 seconds and the PMT2 will digitally re-zero. It is
recommended to re-zero after a filter failure or filter changes. Re-zeroing should only
be done when there is no air flow in the duct.
Averaging Time Selection Switch
The PMT2 will average the output for the selected amount of time. This will dampen
output spikes caused during normal filter cleaning cycles.
Range and Test Selection Switch
There are 6 sensitivity ranges that can be selected based on the material the PMT2
will be sensing (see Table 1). There is also an option to output a 4 mA or 20 mA signal,
these options can assist in the installation of the transmitter or trouble shooting.
Averaging
time
Grounding
screw
Figure 2
Zero switch
Range and
test