Digital Panel Meters By Application
PD6600 Loop Leader Loop-Powered Intrinsically Safe & Nonincendive Process Meter
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Further enhancing the display on these instruments is a 20-segment bargraph available on the PD6608 that also includes a numeric value of the percentage the bargraph represents. There is even a model that displays level in feet and inches for customers who prefer to see their levels represented that way rather than in decimal format.
These loop-powered meters can be installed virtually anywhere because they get their power from the 4-20 mA loop and therefore require no separate power source. And they only drop 1.5 V (4.7 V with backlight), so they add very little burden to the loop. Additional features that allow these instruments to be installed virtually anywhere include a NEMA 4X, IP65 front panel, an operating temperature range of -40 to 158°F (-40 to 70°C), conformally coated PCBs, and a backlit LCD that can be read in bright sunlight or dimly lit areas. Finally, they are intrinsically safe and nonincendive, so they can be installed in hazardous areas.
Free, PC-based, software that connects to the meter via a micro USB cable is available for programming and setup of the meters. In addition, the meter can be programmed, setup and operated via the four front panel buttons. Three of these buttons can be used as function keys. In addition, a digital input is standard and is particularly useful for remote reset of the alarms or to trigger an alarm.
All models come equipped with two open collector outputs and are available with two solid state relays and 4-20 mA analog output options. The open collector outputs are useful for alarm indication or pulse output. The relays can be programmed for alarm indication, on/off control, or pump alternation.
The Loop Leaders display provides multiple ways to help users understand and keep track of their processes. The most obvious is the dual line which typically allows the user to display a numeric value of the process variable on the top line and units and/or a tag on the bottom line. There is also a bargraph that includes a numeric value of the percentage the bargraph represents. Finally, to alert users to an alarm condition, the display can turn red and flash an alarm message.
Dual-Line Display with PV/Units/Tag/Bargraph
One of the most common configurations of these instruments is displaying the process variable on the top line and units and a tag toggling on the bottom line with a bargraph for additional clarity:
The max & min readings (peak & valley) reached by the process can be displayed either continuously or momentarily:
Any of the F1-F3 function keys (buttons) and the digital input can be programmed to reset the max & min readings.
Feet & Inches Display with Bargraph
There are Loop Leader models available for users that prefer to see their level displayed in feet & inches instead of decimal format. These versions can display level to 999FT 11IN & 15/16 on the top line. The bottom line can toggle between a tag and units or if dual scale mode is used, can display the input in a different scale such as volume.
Change Between Units without Needing to Re-Scale the Meter
It is possible to change the display units within the selected unit class without the need to re-scale the meter. When selecting a new unit from within the DISPLAY menu (e.g. changing from gallons (GAL) to liters (L)), the meter will automatically convert the display values to display the new unit. If entering a custom unit (CUSTM), a custom conversion factor will need to be entered.
To help users get a quick understanding of where their process is at, certain Loop Leader models are available with a 20-segment bargraph. This bargraph also includes a numeric value of the percentage the bargraph represents.
Bargraph Provides Quick Understanding
To help users get a quick understanding of where their process is at, certain Loop Leader models are available with a 20-segment bargraph. This bargraph also includes a numeric value of the percentage the bargraph represents. The bargraph can be programmed to represent the percent of PV1 or PV2 or it can be scaled to any range within the scale.
Dual-Scale Display Feature
Users can use the Loop Leaders dual-scale feature when they want to show the same input in two different scales. For instance, the following example shows an application where the Loop Leader displays the input in feet and gallons:
Predefined and Custom Units
The meter has six available preprogrammed unit classes, volume, height, temperature, pressure, weight, and rate. When the desired unit class or unit of measure within a class is not available, a custom unit may be programmed by using the (CUSTOM) menu.
The tare function zeroes out the display. In the case of scale weight, tare is used to eliminate container weight and provide net weight readings. The captured tare may be reset manually with any function key or digital input.
Alarms Indicated by Flashing Red Messages
When an alarm occurs, the Loop Leaders display can be programmed to turn red and flash an alarm message along with the process variable and an alarm indicator (!). (Alarm indicator symbols are not available on bargraph models) The Loop Leaders flashing red alarm message can be activated even if no relay or open collector is connected.
Loop Leaders are available with two open collector outputs as standard and two solid state relays and 4-20 mA output as options. The open collector outputs and relays generally operate in the same manner, with the major exception being the open collectors are not available for pump alternation and the relays are not available with pulse features. The open collectors and relays can be controlled either automatically or manually. The alarm status (with flashing red message) will show on the display even with no output wired.
Two Open Collector Outputs
The Loop Leader is equipped with two NPN open collector outputs that may be set up for pulse outputs, alarms, timed pulses, stopwatch on/off, or disabled. Pulse outputs can be set to transmit the PV value (PV1 or PV2 if meter is in dual-scale mode). Output 2 may be used to generate a quadrature output based on the other open collector output. An output test mode is also selectable to generate pulses at a constant programmable frequency.
Two Optional Solid State Relays
The meter is optionally equipped with two solid state relays that may be set up for alarms, timer, stopwatch on/off, or pump alternation. The relays are rated at 250 VAC/DC @ 1 A for resistive loads and 75 VA @ 0.6 A, 250 VAC/DC max (Safe Area only) for inductive loads. Alarms are available based on the PV value or the digital input.
Loop-Powered Relay Alarm Trip
The Loop Leader, with its two solid state relays, can be used as a loop-powered relay alarm trip. The Loop Leaders two relays can be programmed for two different kinds of latching operation: Reset via momentary contact closure at any time or reset via momentary contact closure only after the alarm has cleared. And the Loop Leader's display can be programmed to turn red and flash an alarm message something not found on most loop powered alarm trips.
Optional Isolated 4-20 mA Output
The isolated analog output signal can be configured to represent the process variable (PV1, PV2, or retransmit). While the output is nominally 4-20 mA, the signal will accurately accommodate underand over-ranges from 1 to 23 mA. The output can be reverse scaled such that the meters high calibration value outputs 4 mA and the meter's low calibration outputs 20 mA.
Resetting the Open Collectors and Relays
The open collectors and relays (alarms) may be programmed to reset in the following ways:
All versions of these instruments are CE marked. The hazardous area versions of these instruments are UL and C-UL Listed as intrinsically safe and nonincendive and ATEX and IECEx Certified for Intrinsic Safety in Hazardous Areas (Gas Atmospheres). These versions are also UL and C-UL Listed under the UL 61010-1 General Safety Standard.
One of the most useful aspects of the hazardous area approvals is that these instruments are approved by UL as nonincendive so they can be installed in Division 2 areas with no additional protective devices needed.