Moore Industries DCA S, DCA H2, DCA H1, DCA D, DCA L2 User Manual
...
May 2016
DCA
Direct Current Alarm
USER’S MANUAL
No. 192-701-00 K
© 2012 by Moore Industries-International, Inc.
Table of Contents
Introduction 1
Description 1
Calibration 4
Installation 19
Maintenance 22
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Page 1
DCA
Introduction
Moore Industries’ Direct Current Alarm (DCA) is a
highly versatile, fully adjustable device that is factoryconfigured to accept either current or voltage input.
The unit’s internal relays are tripped when input
deviates from a customer-set “safe” range defined by
adjustable trip points. The DCA is ideal for use in an
alarm system, where it may be used to activate a
warning device, or to drive an analog indicator.
This manual provides a brief description of the DCA,
including its physical characteristics and options; a
table of performance and operating specifications; a
set of procedures for calibrating the unit; instructions
for installation, including physical mounting and
electrical connections; and finally, information on
basic maintenance and troubleshooting.
Notes, Cautions, and Warnings are included as a
means of identifying those practices that may present
unnecessary inconveniences (notes), result in damage to the unit (cautions), or cause injury (warnings).
bination of single, dual, high, low, fail-safe, or non-failsafe alarm relays. The following paragraphs describe
each of these configurations.
High Alarm/Low Alarm. A DCA configured as a high
alarm is tripped when the input increases, and
reaches a customer-set trip point. A low alarm unit is
tripped by a decreasing input that drops below a
customer-set trip point.
Figure 1 illustrates the concept.
Fail-safe/Non-fail-safe. A fail-safe unit’s relay is
energized when input is within a “safe” range, i.e. is
normal, or not in an alarm condition. When the input
goes into an alarm condition, reaching a trip point or
losing power, the relay of a fail-safe DCA is deenergized.
Conversely, a non-fail-safe unit’s relay is de-energized
when input is within the customer-specified “safe”
range, and is energized when the input reaches the
trip point setting.
Figure 1 also depicts the action of fail-safe relays.
Description
The DCA comes in either Moore Industries’ standard
(STD) or plug-in card (PC) housing.
The STD unit can be used with a variety of mounting
options, including those suitable for use with explosion-proof and NEMA enclosures.
PC-style DCA’s are designed for use with Moore
Industries’ multi-position card racks; the surface
mounted SMR, or the rack mounted RMR.
Both STD and PC DCA’s are available with either
single or dual alarm configurations. The relays used
are single-pole/double-throw, form C. There are a
number of input ranges and alternate relay ratings
available.
Operationally, the unit can be ordered with any com-
Controls and Indicators
Every type and configuration of DCA comes with
potentiometers (pots) to set the alarm trip points of
each installed relay. Additional pots for controlling
unit dead band are available as an option, and precision ten-turn vernier scales can be used instead of
the standard pots.
Trip point pots afford full 0- to 100-percent adjustability over the unit’s specified span.
Each installed relay is wired to a front panel LED,
which lights when the relay is energized. Depending
upon the type of relay ordered, i.e. fail-safe/non-failsafe, a lit LED can indicate either an “alarm” or a “nonalarm” input condition.
Table 1 summarizes the alarm type/LED status
options for the available types of DCA.
Page 2
DCA
100 %
ANALOG
INPUT
VALUE
0 %
Model Number
Designator
HIGH-ALA RM DCA
TIME
100 %
TRIP POINT
DEAD BAND
RESET
FAIL-SAFE R ELAY ENERGIZED , LED ON
FAIL-SAFE R ELAY DE-ENERGIZED, LED OFF
ANALOG
INPUT
VALUE
0 %
LOW-ALARM DCA
RESET
DEAD BAND
TRIP POINT
TIME
Figure 1. High - and Low-alarm Relay Configurations
Table 1. DCA Alarm Types
This Unit is...
S Single Alarm - - Only one relay installed
This Unit signals an
“Alarm” condition when...
Its LED will be...
Relay(s)
D Dual Alarm - - Two relays are installed
H1 High Fail-Safe
H2 High NON-Fail-Safe
L1 Low Fail-Safe
L2 Low NON-Fail-Safe
Input increases, and exceeds
Trip Point. (See Note 2).
Input increases, and exceeds
Trip Point. (See Note 2).
Input decreases, and drops
below Trip Point
(See Note 2)
Input decreases, and drops
below Trip Point
(See Note 2)
OFF in alarm
ON in Non-alarm
ON in Alarm,
OFF in Non-alarm
OFF in alarm
ON in Non-alarm
ON in Alarm,
OFF in Non-alarm
DE-energized in alarm
Energized in Non-alarm
Energized in Alarm,
DE-energized in Non-alarm
DE-energized in alarm
Energized in Non-alarm
Energized in Alarm,
DE-energized in Non-alarm
NOTES: 1. Older DCA’s may use X1 for H1, X2 for H2, X3 for L1, and X4 for L2.
2. The “UPPER” and “LOWER” labeling on the DCA front panel is for reference only.
Configurations where “LOWER” terminals and pots pertain to the unit’s high alarm, for
example, are quite possible.
3. Relays in fail-safe alarms are DE-energized in the event of power loss to the unit.
Page 3
DCA
Table 2 lists the performance and operational specifications for the unit.
Table 2. DCA Performance and Operational Specifications
Characteristic
Input
Output
Specifications
Current: 1-5 mA @ 200Ω nominal input impedance
4-20 mA @ 50Ω nominal input impedance
10-50 mA @ 20Ω nominal input impedance
Selectable Current (SC) comes with three load resistors for selecting1-5, 4-20, or
10-50 mA (See Note 1)
Voltage: 0.25-1.25 V @ 1MΩ, minimum (See Note 2)
1-5 V @ 1MΩ, minimum
Consult factory for dual input and special range options.
Factory-configured with one (Single DCA) or two (Dual DCA) single pole/double throw
(SPDT), form C, mechanical relays rated for 5 A @ 117 Vac non-inductive, or 28 Vdc.
User selects Normally Open (NO), Normally Closed (NC), or any combination of NO/NC
configurations during installation. Fail-safe/Non-fail-safe configuration factory-set. Refer to
table 1 for available combinations.
Options
Each DCA is configured according to customer
requirements. The paragraphs on the following pages
highlight some of the options available.
Power
Performance
Environmental
Ratings
NOTES: 1. One of the available resistors MUST be installed.
2. Requires extra engineering when used with some option combinations.
3. DPDT not available with some enclosures and option combinations.
Double pole/double throw (DPDT), form 2C and 7.5 A relays available as options.
(See Note 3)
24 or 45 Vdc ±10%, 5 watts nominal
100, 117, 200, 220, or 240 Vac ±10%, 50/60 Hz
AC power inputs not available with PC-style housing
Repeatability: Trip point settings repeat within ±0.1% of span.
Dead Band: 1% of span, standard. Adjustable Dead Band Option available.
Alarm Response: 50 milliseconds for step change of 1% of span.
Line Voltage Effect: ±0.005% per 1% line voltage change (ac or dc).
Isolation: No galvanic path between input, output, and power.
Accuracy: Front panel potentiometers capable of setting trip points from 0 to 100% of
span. Lockable, scaled vernier dials optional.
Effect of Ambient Temperature on Performance: Less than ±0.018% per °C through the
specified range (Less than ±0.01% per °F)
Ambient Operating Temperature: –18 to 65 °C (0 to 150 °F)
Page 4
DCA
For a complete list of available options, and for
information on other housings, mounting hardware,
and enclosures, contact your Moore Industries Sales
Representative.
AD Option —
Front panel potentiometers vary dead band 1- to 20percent of span (nominal), 1- to 50-percent of span
(AD50), or 1- to 100-percent (AD100) of span. (AD
Option not available with some option combinations).
AR Option —
factory for output delays of 1 to 5, 10, 15, 20, 25, or
30 seconds, according to customer specification.
DA Option —
condition when the difference between two inputs
exceeds adjustable percent of full span. Requires DI
Option or 2X input. (Not available with some option
combinations.)
DI Option —
to operate as two, single-alarm units. Standard DI
unit provides a high alarm for one input and a low
alarm for the other. (DI Option not available with
some option combinations).
DPDT Option —
Relays. Contact 5 amps at 28 Vdc, or 117 Vac noninductive. (DPDT Option not available with some
option combinations).
Externally-adjustable Dead Band.
Response Time Delay. Set by the
Deviation Input. Unit signals alarm
Dual Input. Configures dual-alarm DCA
Double Pole, Double Throw/Form 2C
TX Option
at 30 Vdc @ 25 mA.
7.5A Option —
UL at 7.5 amps, 28 Vdc or 120 Vac.
Model/Serial Number. Moore Industries uses a
system of unit model and serial numbers to keep
track of factory configuration and options for each
DCA shipped and serviced.
The example outlines the significance of each field of
information in a typical DCA model number. Refer to
table 1 for an explanation of the relay configuration
codes used.
If service information or assistance for a DCA is
needed, make a note of the unit’s model and serial
number before contacting Moore Industries’ Customer
Service Department. Our highly skilled technicians
will be happy to assist you.
STD units’ serial and model numbers are located on
an L-shaped metal tag at the top of the connection
terminal strips. On PC DCA’s, the numbers are
located on an adhesive label affixed to the side of the
front panel.
— Two-wire Transmitter Excitation. Rated
7.5 amp Relay(s). Rated by CSA and
Calibration
FU Option
PC-style unit. Use of the FU Option with the STD
housing requires special engineering.
HS Option
@ 117 Vac non-inductive, 2A @ 28 Vdc. Meets
requirements for installation in Class I, Division 2
locations.
MR Option —
button for single- and dual-alarm units. In place of
dead band, MR-equipped units return to normal only
when the process input returns to non-alarm state
the external reset push button is pressed.
TT Option —
multiturn potentiometers for setting and locking trip
points. Includes front panel ZERO potentiometer for
appropriate offsets.
— Power Fuse. 400 mA rated fuse on
— Hermetically Sealed Relays. Rated 1A
Manual Reset. External reset push
and
Lockable Vernier Dial. Front panel,
Every DCA shipped from the factory is manufactured
and tested according to Moore Industries’ exacting
standards for product quality. A bench check of basic
unit operations is recommended, however, in order to
identify any damage to the unit that may have occurred during shipping. This also allows the user to
effect operational adjustments to trip point settings
and unit dead band, if available.
It is recommended that the procedures in this section
be carried out at a technician’s bench or in a similar
lab environment. This is the safest means of making
adjustments to trip point values; isolated from the
intended DCA application.
The calibration of the DCA consists basically of
setting trip points and dead bands based on the
resistance across the unit contact-closure terminals
as measured by an ohmmeter. With relay contacts
closed, resistance is negligible. With relay contacts
open, resistance is infinite.
EXAMPLE
Unit Type
Input
Relay Configuration
Power
Options(s)
Housing
Page 5
DCA
DCA / 4-20MA / DH1L1 / 117AC / -AD [STD]
Basic Calibration Setup
The equipment listed in table 3 is needed for calibrating the DCA. These items are not supplied with the
unit, but should be available in most testing labs.
Table 3. DCA Calibration Equipment
Equipment Specifications
Voltage
Voltage or
Current Source
Current Source
Power Source
Ohmmeter Accuracy of ±1%, minimum.
Screwdriver Slotted-tip with head width no greater than 2.54 mm (0.01 in).
Wire Jumpers
(required for
AR-equipped
DCA’s ONLY)
or
Calibrated, adjustable unit, capable of output at discrete levels in the
appropriate range, with the rated impedance for the unit being calibrated.
EDC Models MV105, MV155, or equivalent.
AC or dc power input appropriate for the type of DCA being calibrated.
Refer to table 2, earlier in this manual.
Temporary jumper wiring suitable for shorting AR Option diodes so that the
alarm delay may be defeated while adjusting the unit’s trip point settings.
Be sure to use calibrated test equipment when
performing the bench check and calibration of the
DCA. The use of inaccurate test equipment may
result in unreliable settings for the unit’s trip point(s),
etc.
Extender Card
(optional for use
with PC-style
DCA’s ONLY)
Moore Industries’ part number 350-513-00.
Page 6
DCA
Setup for the STD DCA. Figure 2 shows the labeling
used on the front panel of the STD DCA. Figure 3
shows the terminals on a unit equipped with DPDT
relays.
CDC URRENT
DCA
UPPER RELAY NORM ALLY
OPEN — UNO
COMMON — COM
UPPER RELAY NORM ALLY
CLOSED — UNC
ALARM
UPPER LOWER
ZERO
U PPER
D EADBAN D
LOWER
To access the connection terminals for a DCA in the
basic extruded housing (STD, AB, etc.), use a screw
driver to remove the securing screw from the protective plastic cover on the unit front panel. With the
screw removed, the cover can be removed by hand,
revealing the terminals and the labels depicted in the
illustrations in this manual.
LNO —
LOW ER R ELAY N ORM ALLY OPEN
COM — COMMON
LNC —
LOWER RELAY NORMALLY CLOSED
ACC — –DC
AC — +DC
GND
NOTES: 1. Each uni t i s factor y- configured for ac or dc pow er .
2. Each unit is factor y-c onfi gur ed for specifi c cur r ent or voltage input.
Figure 2. STD DCA Terminal Locations
OPTION — +TX FOR TRANSMITTER
EXCITATION, +REF FOR D EVIATION ALARM
+IN — CURRENT OR VOLTAGE +INPUT
-IN — CURRENT OR VOLTAGE -INPUT
UPPER RELAY #1 NOR MALLY
OPEN — UNO1
COMMON — COM
UPPER RELAY #1 NOR MALLY
CLOSED — UNC1
ACC — –DC
AC — +DC
GND
DC CURRENT
DCA
ALARM
UPPER LOWER
ZERO
U PPER
D EADBAN D
LOWER
Page 7
DCA
UN O2 — UPPER RELAY #2
NORM ALLY OPEN
COM — COMMON
UNO2 — UPPER RELAY
#2 NORMALLY CLOSED
LNO1 — LOWER RELAY #1
NORMALLY OPEN
COM — COMMON
LNC1 — LOWER RELAY #1
NORMALLY CLOSED
LNO2 — LOWER RELAY #2
NORMALLY OPEN
COM — COMMON
LNC2 — LOWER RELAY #2
NORMALLY CLOSED
OPTION — +TX FOR
TRANSMITTER EXCITATION,
+R EF FOR D EVIATION ALARM
Figure 3. STD DCA w/DPDT Option Terminal Locations
Figure 4 shows the labeling for a STD DCA equipped
with the DI Option. Note that both inputs share the “–
IN” terminal.
+IN — CURRENT
OR VOLTAGE +INPUT
-IN — CURRENT
OR VOLTAGE -INPUT
WARNING
To guard against accidental electric
shock, it is recommended that the protec-
tive plastic cover be re-installed over the
terminal strip of the STD DCA before
applying power to the calibration setup.
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