Application Notes Using Acromag’s AC current sensor Model 5020-350 Several Acromag transmitters with DC current input can be used used in conjunction with an external AC Current Sensor to precondition an AC current input signal. This sensor is a highly accurate toroidal instrument transformer that converts an AC current signal to a safe, low- level, DC milliampere signal (0 to 11.17mA). The transmitters only accept the isolated low- level signal produced by the AC current sensing transformer and cannot be connected directly to Acromag's Flat Pack transmitters are shown with the AC current sensor toroidal transformer. the source of AC power without damage or safety risk. The AC Current Sensor is fully insu- The output wires of the sensor are polarized: the Sensor lated and designed for mounting near the source Primary AC Current Sensor Output Red wire is (+) plus and the Black wire is (-) of the AC current. The input AC current range is Turns Input Range (red/black wires) minus. Normally, these output wires are a simple function of the number of turns placed 1 0 to 20 Amps AC 0 to 11.17mA DC attached to one end of a cable (user supplied) on the AC Current Sensor (see the table below). 2 0 to 10 Amps AC 0 to 11.17mA DC and the other end connects to the transmitter's The benefits to using an external sensor (external 4 0 to 5 Amps AC 0 to 11.17mA DC input. Connect the Current Sensor output leads from the transmitter) include the following: to the transmitter input by connecting Red (+) to 10 0 to 2 Amps AC 0 to 11.17mA DC Low losses: the transmitter's plus (+) terminal, and Black (-) 20 0 to 1 Amps AC 0 to 11.17mA DC It is not practical to run AC currents over long to the transmitter's minus (-) terminal. Proper distances because of significant resistance volt- polarity must be observed. The AC Current Sensor is isolated and can be age drops at high currents. The low-level DC used in AC circuits up to 250V AC, 50 or 60 Hz. milliampere signal output from the AC Current WARNING: It is designed to be mounted at the source of the Sensor can be transmitted safely over long dis- The input to the module can only come AC current to be measured. The transmitter can tances, allowing the transmitter to be remotely from the AC Current Sensor output wires be located remotely from the AC signal and located from the AC power wiring. (red/black). If AC current is directly attached wired using small gauge wire. The sensor's out- to the transmitter's input terminals, the Safety: put wires can be shorted, open-circuited, or transmitter will be destroyed and safety The AC Current Sensor's output leads can be removed from the transmitter's input terminals, compromised. open or short circuited and these conditions without hazard to personnel or the AC Current do not affect the AC current loop or cause Sensor. For most applications, it is recommended that damage to the sensor. Likewise, the wires the minus (-) transmitter input terminal be con- connecting the AC Current Sensor to the DANGER: nected to an earth ground. The connections transmitter can be easily removed from the If the AC Current Sensor is used with an AC between the AC Current Sensor would be float- transmitter's input terminals without concern Current Transformer (C.T.), disconnect power ing if not grounded. Grounding eliminates the or hazard. to the C.T., or short the output of the C.T., risk of high common-mode voltages from show- before removing the wire going through the ing up on the wires and reduces noise pickup. Ease of Calibration: AC Current Sensor. If this is not done, an The AC current input range can be easily open circuited C.T. will generate high volt- Supported Products scaled in the field by simply changing the ages (hazardous) and possible C.T. damage.IntelliPack Series Transmitters and Alarms number of primary turns at the sensor, with no additional calibration required. That is, the610T Series Isolated Transmitters AC current input span is a simple function of ACR Series Isolated Transmitters the number of primary turns placed on the AC Current Sensor and sensor/transmitterFlat Pack 250T/350T/450T Series Transmitters calibration is not affected by this. Refer to and 361A/461A Series Alarms Applications "A" & "B" of the diagrams on ® SmartPack Series LONWORKS I/O Modules the next page. Tel: 248-624-1541 Fax: 248-624-9234 e-mail: sales@acromag.com www.acromag.com 189 Application Notes Dimensions and Electrical Connections Tel: 248-624-1541 Fax: 248-624-9234 e-mail: sales@acromag.com www.acromag.com 190 Application Notes Application Examples Tel: 248-624-1541 Fax: 248-624-9234 e-mail: sales@acromag.com www.acromag.com 191