发明名称 |
Current loop input protection |
摘要 |
A protective circuit for a process control device such as a valve actuator, for example, prevents damage to device components. In particular, a protective circuit allows an analog current loop (e.g., 4-20 mA) to provide to a device component a secondary operating voltage, derived from the analog current loop, in the absence of a primary operating voltage source (e.g., during a power failure), such that the device component is not damaged when a signal from the analog current loop is applied to the process control device in the absence of the primary operating voltage source. |
申请公布号 |
US9337650(B2) |
申请公布日期 |
2016.05.10 |
申请号 |
US201314012468 |
申请日期 |
2013.08.28 |
申请人 |
FISHER CONTROLS INTERNATIONAL LLC |
发明人 |
Eisenbeis Clyde T. |
分类号 |
H02H9/04;H02J3/00;H02J9/00 |
主分类号 |
H02H9/04 |
代理机构 |
Marshall, Gerstein & Borun LLP |
代理人 |
Marshall, Gerstein & Borun LLP |
主权项 |
1. A protective circuit in a process control device for protecting a component of the process control device, the protective circuit comprising:
a current loop input operable to receive a current proportional to an indicated value; an operating voltage input, separate from the current loop input, configured to couple to a voltage source and to receive from the voltage source a primary voltage signal, the operating voltage input further operable to power the component such that the process control device operates to control a process according to the indicated value; and a plurality of protective circuit components configured to:
provide a secondary voltage signal to the component from the current loop input when the primary voltage signal is below a first threshold, andprovide the primary voltage signal to the component from the operating voltage input when the primary voltage signal is above the first threshold. |
地址 |
Marshalltown IA US |