aca-20rm-alm series true-rms-ac ammeters with alarm function for full details go to www.murata-ps.com/rohs www.murata-ps.com/dpm www.murata-ps.com email: sales@murata-ps.com 10 nov 2010 mpm_aca-20rm-alm.a03 page 1 of 5 murata power solutions aca-20rm-alm series digital ac ammeters accurately display the true-rms value of non-sinusoidal ac currents and provide a user-settable, over current alarm function. when the preset over current level is exceeded, the led display continu- ously ? ashes from high to low intensity. all models are totally self-containedno other user-supplied components are required. a built-in current transformer greatly simpli? es most ac ammeter applications: just pass the load conductor through the built-in current transformer, apply ac power, and the ammeter is fully operational. two input ranges are available: 0-30.0 amps, or 0 to 50.0 amps, both with 0.1a resolu- tion. the 50 amp model features a convenient split-core type current transformer which can be clamped around insulated live conductors. two power supply options are available: 85-140v (47-63hz), and 170-264v (47-63hz). power consumption from a nominal 120v or 220v ac supply is less than 50ma. super-stable components and an rms-to-dc converter circuit combine to achieve excellent performance when measuring the complex, non-sinu- soidal, ac currents found in todays computer/telecom equipment. all aca-20rm-alm series true-rms ammeters feature full-size, 0.37 " (9.4mm) high, 3? digit, bright red led-displays and a built-in bezel/? lter assembly that includes metal fasteners. they are also panel cutout compatible with mpss dms-20rm series of rms- reading ac voltage monitors, making aca-20rm-alm ammeters the ideal upgrade for todays sophisticated instrumentation. features userCsettable, visual alarm function flashing display indicates overcurrent faults measures the true-rms value of complex ac current waveforms includes built-in current transformers ideal for measuring current in sensitive it applications available in two input ranges: 0-30.0a, and 0 to 50a 50a model features convenient split-core ct easy-to-read, red led display with 0.37 " /9.4mm high digits two ac power options: 85-140vac & 170-264vac (50/60hz) 2000v isolation between ac supply and load conductor $ ac input power 3? digit a/d converter +v ?v ? + rms-to-dc converter cal. built-in current transformer led display power converter tb1 ab (l1) measured ac load current figure 1. aca-20rm-alm series simpli? ed schematic
aca-20rm-alm series true-rms-ac ammeters with alarm function www.murata-ps.com/dpm email: sales@murata-ps.com 10 nov 2010 mpm_aca-20rm-alm.a03 page 2 of 5 technical notes important! to ensure safe and reliable operation, aca-20rm- alm ammeters must be installed and serviced by quali? ed technical personnel. contact murata power solutions if there is any doubt regarding ammeter setup, installation, or operation. 1. measurement type: aca-20rm-alm ac ammeters employ a true-rms input circuit to measure current ? owing through l1. stated accuracy speci? cations are measured using a sine-wave current at, or close to, the ammeters full-scale input range, at nominal line frequency of 60hz. 2. calibration (potentiometer r7): periodic recalibration of aca- 20rm-alm ammeters is not required under normal, indoor operating environments. if user calibration is necessary, it must be performed by quali? ed technical personnel. calibration is performed with poten- tially lethal voltages applied to the aca-20rm-alm and its associated wiring. a plastic, fully-insulated adjusting tool must be used to access the calibration potentiometer r7 located on the back of the ammeter (see mechanical speci? cations section). contact mps if additional information is required regarding calibration, setup, or any other technical issue pertaining to aca-20rm-alm ammeters. 3. overcurrent alarm setup and adjustment (potentiometer r3): aca-20rm-alm ammeters feature a user-settable, overcurrent visual alarm indication which can be used to alert operators that a load cir- cuit breaker or fuse is approaching an overload condition. when the load current sensed by l1 exceeds this preset level, the ammeters led display will ? ash from normal intensity to dim intensity at rate of approximately 1.5 times per second. as shown in figure 3, the alarm circuit consists of jumper jp1, and adjustment potentiometer r3. as shipped, r3 is factory set to trip when the load current is approximately 24 amps for 30a models, and approximately 45 amps for 50a models. when r3 is set to its maxi- mum clockwise position, the alarm indication will not activate until the load current ? owing through l1 exceeds the maximum rating of the ammeter, i.e., above 30.0a, or above 50.0a, depending on the model. performance/functional speci? cations typical at t a = +25c, unless otherwise noted. ? speci? ed full-scale currents are those passing through the ammeters built-in current transformers primary load-circuit. see notes 2 and 3 below for ad- ditional model-speci? c information. ? the overcurrent rating of 1.5 x the rated full-scale current is a continuous rating and applies to the current passing through the built in current transformer only, it does not apply to any external circuit-wiring or external loads. accuracy is guaranteed up to the rated current level. ? speci? ed accuracy applies to inputs with crest factors (cf) up to 2.0, where cf = vpeak/vrms. crest factors of 2 to 5 introduce an additional error of 3% of full scale. ammeters are calibrated with a near full-scale 60hz sine-wave current ? owing through the ammeters built-in ct. ? all speci? ed maximum power supply currents are steady state; larger surge currents can occur at initial application of line power. rated full-scale current ? min. typ. max. units aca-20rm-4-acx-rl-alm 50.0 amperes aca-20rm-5-acx-rl-alm 30.0 amperes overcurrent rating ? 1.5 x rated full-scale current performance sampling rate 2.5 samples per second accuracy ? 0.4%fs 3 counts with 60hz sine-wave input measurement type rms responding, crest factors of 1-5 temperature drift (0 to 60 c) 0.2 0.4 counts/oc zero-current reading (within 30 sec.) C001 000 001 counts dielectric withstanding voltage 2000 vdc power supply voltage aca-20rm-x-ac3-rl-alm 85 120 140 vac/47-63hz aca-20rm-x-ac4-rl-alm 170 220 264 vac/47-63hz power supply current ? aca-20rm-x-ac3-rl-alm 30 50 ma/47-63hz aca-20rm-x-ac4-rl-alm 30 50 ma/47-63hz alarm function display indication flashing display with actual current reading and display intensity change settable range aca-20rm-4-acx-rl-alm 13 45 50 amps aca-20rm-5-acx-rl-alm 8 24 30 amps power supply terminal block wire size 16-22awg, solid or stranded insulation strip length 0.250 inches screw tightening torque 3.6 pounds-inches (0.4nm) rated voltage 310vac display display type and size 3? digit red led, 0.37/9.4mm high overrange indication 1___ decimal point fixed, model dependent (see full-scale input current) physical/environmental operating temperature 0 +60 c storage temperature C40 +75 c humidity (non-condensing) 0 85 % dimensions model dependent, see page 4 & 5 weight aca-20rm-4-xxx-xx-alm 1.5 ounces (43 grams) nominal aca-20rm-5-xxx-xx-alm 2.1 ounces (60 grams) nominal ordering information aca-20rm-4-ac3-rl-alm-c 50.0a range (split-core ct), 85-140vac power aca-20rm-4-ac4-rl-alm-c 50.0a range (split core ct), 170-264vac power aca-20rm-5-ac3-rl-alm-c 30.0a range, 85-140vac power aca-20rm-5-ac4-rl-alm-c 30.0a range, 170-264vac power
aca-20rm-alm series true-rms-ac ammeters with alarm function www.murata-ps.com/dpm email: sales@murata-ps.com 10 nov 2010 mpm_aca-20rm-alm.a03 page 3 of 5 6. connector torque ratings: it is important to tighten tb1s, screw- terminals to their rated torque speci? cation of 3.6 pound-inches (0.4nm). proper tightening will minimize connector losses and ensure safe, reliable operation. 7. isolation: the built-in current transformer l1 provides a minimum of 2000vdc isolation between the load conductor and the ammeters supply voltage connected to tb1. 8. split-core ct (clamp-on) models: both 50a models feature a split- core current transformer that can be clamped around a properly insu- lated live conductor without having to disconnect or remove power from the load circuit. this live-connection capability can only be used if the loads power source is electrically isolated (see technical note 7) from the ammeters own power source thats connected to tb1. the ammeters ac power supply must always be denergized before making connections to tb1. refer to the panel installation section of this data sheet for additional information. l1 to ac load tb1 back view a b fused ac power figure 2. typical wiring diagram to adjust the overcurrent alarm set-point level: a. turn off power to the aca-20rm-alm (i.e., the power source con- nected to tb1). b. carefully remove the shorting jumper across jp1 from its normal operation position across terminals 2 and 3 and place it across jp1 terminals 1 and 2. c. re-apply power to tb1 and, using a plastic insulated adjusting tool, adjust r3 so the ammeters display shows the desired overcurrent trip level in amps. d. turn off power to the aca-20rm-alm and return jp1a shorting jumper back to its normal operation position across terminals 2 and 3. re-apply power to tb1 to resume normal operation. if pos- sible, after the ammeter is re-con? gured for normal operation, the load current should be slowly increased to verify the visual alarm operates when the load current exceeds the preset level. please note, the load circuit does not need to be turned off to adjust the overcurrent alarm set point. current ? owing through l1 while jp1 is across terminals 1 and 2 will not be measured. once tripped, the alarm set point function has a hysteresis of approximately 0.5a. the overcurrent alarm function can also be adjusted with jp1 in its normal operation position if the desired alarm overcurrent-level is actually ? owing through l1 (i.e., with a live load). for example, with a 20 amp load current ? owing through l1, and with jp1 in its normal operation position, slowly adjust r3 until the display starts ? ashing on and off. using this live load adjustment method eliminates the need to turn off power to tb1 or recon? guring jp1. 4. wire gauges and fusing: wires speci? ed in the functional speci? ca- tions section must be used for making connections to aca-20rm-alm series ammeters. all power-supply and load wiring must be rated for the supply voltages and currents they will conduct and must comply with any code or application-mandated requirements pertaining to the users speci? c installation. the supply wires connected to both the ammeter and the load must be fused according to the current rating of the wire gauge being used, in accordance with applicable regulatory codes. also, wire insulation should be stripped to within +/C10% of the stated dimensions, and wires should be inserted into tb1 such that their insulation is not pinched by the screw terminal. tb1 is to be used only for powering the meters internal circuitry, it must not be used to supply current to external loads. all models draw minimal steady-state supply currents (50ma max.), and in most applications, they can be fused according to the supply wires maximum amperage rating. however, these products can draw signi? cantly higher surge currents for brief periods when the ac line voltage is initially applied. 5. ac supply polarity and grounding: the two supply inputs, tb1-a and tb1-b, on aca-20rm-alm ammeters are not in themselves polarity sensitive, that is, they have no internal ac lo or ac hi designa- tions. aca-20rm-alm ammeters do not include or require a connec- tion to earth/chassis ground. figure 3. alarm circuit component location tb1 r7 cal jp1 back view r3 alarm jp1 normal operation 3 2 1 jp1 overcurrent alarm adjustment 3 2 1 3 2 1
front v iew 1.280 (32.51) 0.187 (4.75) recommended d rill a nd panel c utout d imensions 1.826 ( 46.38) 0.838 (21.29) 1.626 ( 41.30) 1.07 (27.18) internal c orner r adii: 0.032 ( 0.81) m ax. 0.093 ( 2.362) d iameter ( 4 r equired) 0.116 ( 2.95) 1.336 ( 33.93) 0.145 ( 3.68) 0.69 (17.5) aca-20rm-alm series true-rms-ac ammeters with alarm function www.murata-ps.com/dpm email: sales@murata-ps.com 10 nov 2010 mpm_aca-20rm-alm.a03 page 4 of 5 panel installation bezel and panel cutout all connections to aca-20rm-alm series ammeters must be made after the ammeter is securely attached to the panel and with all associated load and supply voltages de-energized (off), using extreme caution and observing all safety measures applicable to the users installation. care should be exercised when passing conductors through the amme- ters built-in current transformer l1. the installed wire-positions should be such that minimal mechanical forces are applied to l1, tb1, or to the ammeter itself. in high-vibration environments, it is strongly recom- mended that adequate strain reliefs be used for all wiring. using figure 4 as a guide, carefully insert the bezel/color ? lter assembly into the panel opening. from the rear of the panel, install the four round figure 4. panel installation plastic standoffs over the bezels threaded studs. install the aca-20rm- alm pc-board assembly as shown and then attach and securely tighten all four hex nuts. use only the factory-supplied hardware as the use of substitute hardware could result in an unsafe installation and/or adversely affect the reliability of the ammeter. the recommended range of panel thickness that can be used with the supplied hardware is 0.040 inches (1.0mm) to 0.125 inches (3.2mm). panel thickness outside of this range will require additional user-supplied hardware or modi? cations. side view bezel gasket standoff nut aca-20rm ac ammeter board-cutout panel gasket standoff 0.190 (4.83) 0.032 (0.8) thick
aca-20rm-alm series true-rms-ac ammeters with alarm function murata power solutions, inc. makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. the descriptions contained her ein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. speci? cations are subject to cha nge without notice. ? 2010 murata power solutions, inc. www.murata-ps.com/locations email: sales@murata-ps.com murata power solutions, inc. 11 cabot boulevard, mans? eld, ma 02048-1151 u.s.a. iso 9001 and 14001 registered 10 nov 2010 mpm_aca-20rm-alm.a03 page 5 of 5 mechanical specifications mechanical dimensions: inches (mm) tolerances: 2 pl dec 0.02 (0.51) 3 pl dec 0.010 (0.254) front view back view side view 100-10 m9 100-10 m9 2.100 (53.34) 1.400 (35.56) 0.250 (6.35) 30 amp models 0.480 (12.19) lead length 2.0 (50.5) min. a b b1 0.35 (8.9) diameter front view back view side view 100-10 m9 100-10 m9 2.100 (53.34) 1.400 (35.56) 0.250 (6.35) 50 amp split-core ct models 1.024 (26.01) 0.551 (14.00) 0.984 (24.99) 1.575 (40.00) 0.480 (12.19) 0.40 (10.2) diameter lead length 5.0 (127.0) min. a b tb1
|
