Edge Guider Connections
July 12, 2011Linear Actuator Controller; Edge Guiding
July 14, 2011Current Sensing Circuit: Benefits, Applications, Products
A current sensing circuit or board monitors electronic current flow in a number of applications. How does it work? Current sensors are able to monitor the current by measuring the drop in voltage for a resistor, which is placed in the direct path of the current. This is often referred to as “shunt resistor current measurement.” The current sensing circuit creates a proportional current or voltage output to the current in the path being measured.
Low Side and High Side Current SensingThere are two methods of current sensing: low side current sensing and high side (traditional method). With the low side technique, the current sensing circuit is connected between the load and the ground, and voltage drop across the resistor between load and ground is what is used to determine the measurement of the current. Low side current sensing has a a few benefits. It is inexpensive and fairly easy and straightforward to implement. The only cons to this type of sensing are that it may sometimes need additional wiring for the load and it also adds additional unwanted resistance to the ground path. |
The high side technique involves connecting the circuit between the supply and the load. Just like with low side current sensing, the voltage drop of a resistor is used to determine the measurement of the current (with the resistor being between the supply and load). This method allows for the current sensing circuit to be connected directly to the power source. Failures can also be detected and corrected easily. This type of current sensing method requires that the circuit be able to withstand very high voltages, and it also involves the need to match the resistor very carefully to reach a correct CMMR (common-mode rejection ratio).
Applications for Current Sensing Circuits or Boards
There are a number of applications that can benefit by measuring the flow of a current. Though this measuring process has been used mainly to protect circuits and to report measurements in the past, it’s now becoming a popular way to monitor and sometimes even enhance performance, particularly in fast-paced work environments.
A few applications for current sensing circuits include programmable sources of a current, battery chargers, the supervision of circuits and over-current protection on motors and machinery, power supplies (switch-mode and linear), circuits that are operated by battery, and many others. It can also be used in industrial motor control for heavy duty AC and DC motors.
Carotron, Inc. provides a Current Sensing Board, Model C10748-XXX that can be used for sensing AC and DC current while providing isolation. It can be used to measure current for DC motors as well as line operated AC motors. The Current Sensing Board can be used to measure motor current out of electronic soft starters. More information can be found on the main product page.
Resource/Copyright Info: This motor control article about current sensing circuits is under © Copyright of Carotron, Inc., your source for high quality DC and AC motor drives and other industrial motion control products to keep your operation running smoothly.