the 20alm is an input loop powered trip amplifier, deriving its power from the input signal n high or low alarm option n low voltage drop n setpoints available on front panel as 0.4 to 2v signal (4 to 20ma) n led indication of alarm n unique low cost solution loop powered trip amplifiers 20alm description the 20alm is a 4-20ma loop powered trip amplifier. the device derives its power from the input signal and therefore requires no external power supply. the output of the 20alm is a single pole, normally open, solid state relay which can be configured to close either above or below the adjustable setpoint. the switched output can be connected to any potential within 1kv of the transmitter supply, while transients of 2.5kv can be withstood. the relay is designed to switch ac or dc. the trip amplifier is typically used to activate a warning or control system override when a sensor output goes above or below a pre-set limit. alternatively, the unit can be used for simple on/off control, having a built in switching hysteresis. the device is housed in an ultra-compact din-rail mounted enclosure, only 18mm wide. recommended operating conditions input current 4-20ma relay contact voltage 24vac/dc or 110vac relay current (max) 300ma @ 24vdc C 130ma @ 110vac output resistance 5 (on) 24v type C 24 on 110vac type environmental conditions storage temperature -40-70?c operating ambient 0-55?c relative humidity 0-90% rh options and ordering codes 20alm axxx C C 8 115vac options 115vac rated contacts 115vac 24vac/dc rated contacts dc s s s 4-20ma 3 4 1 2 n.o. or n.c. solid state relay output 3.4v dimensions specifications 12 34 s s s s s s 63mm 58mm 18mm connection details 1. relay output -ve 2. relay output +ve 3. input channel +ve 4. input channel -ve parameter min typ max comments supply voltage loop power supply current 4ma 20ma full scale volt drop 3.4v 3.5v at 20ma input relay type 1 current 315ma rated at 24vdc/ac relay type 2 current 130ma rated at 110vac output resistance on 5 /24 24v/110vac relay type setpoint hysteresis 50a other values available trip point accuracy 0.25% temperature coefficient 100ppm/?c trip point drift 100ppm/?c relay time response 10ms operating ambient 0?c 55?c relative humidity 0% 90% isolation voltage 1kv surge voltage 2.5kv for 50s transient of 10kv/s notes setpoint is adjusted by 20 turn potentiometers on the front panel. setpoint can be checked by measuring the 0.4 to 2v (4 to 20ma) voltage on the front panel terminals. high or low alarm is selectable using internal link. closed output contact is indicated by a red led on the front panel.
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