Loop Powered Trip Amplifiers 20ALM The 20ALM is an input loop powered trip amplifier, deriving its power from the input signal ■ High or low alarm option ■ Low voltage drop ■ Setpoints available on front panel as 0.4 to 2V signal (4 to 20mA) ■ LED indication of alarm ■ Unique low cost solution PRICE INFORMATION AND ORDERING Options and ordering codes 20ALM 115VAC – AXXX – 8 Options 115Vac rated contacts 115VAC 24Vac/dc rated contacts DC 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. Recommended operating conditions Input current 4-20mA Relay contact voltage 24Vac/dc or 110Vac Relay current (max) 300mA @ 24Vdc – 130mA @ 110Vac Output resistance 5Ω (on) 24V type – 24Ω on 110Vac type Environmental conditions Storage temperature Operating ambient Relative humidity 4-20mA N.O. or N.C. solid state relay output 3.4V ▲ ▲ ▲ 58mm 1 2 ▲ 18mm ▲ 3 4 ▲ Connection details 1. Relay output -ve 2. Relay output +ve 1 4 Typ Loop power Max 2 Specifications ▲ 63mm 3 ▲ The device is housed in an ultra-compact DIN-Rail mounted enclosure, only 18mm wide. Dimensions ▲ 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. -40-70˚C 0-55˚C 0-90% RH 3. Input channel +ve 4. Input channel -ve Parameter Supply voltage Supply current Full scale volt drop Relay type 1 current Relay type 2 current Output resistance ‘ON’ Setpoint hysteresis Trip point accuracy Temperature coefficient Trip point drift Relay time response Operating ambient Relative humidity Isolation voltage Surge voltage Notes Min 4mA 3.4V 20mA 3.5V 315mA 130mA 5Ω/24Ω 50µA Comments At 20mA input Rated at 24Vdc/ac Rated at 110Vac 24V/110Vac relay type Other values available ±0.25% ±100ppm/˚C ±100ppm/˚C 10ms 0˚C 0% 1kV 55˚C 90% 2.5kV for 50µS Transient of 10kV/µS 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.