Receptor: 1. In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds a specific substance. There are many receptors.
The most common is EPNS (Electro Plated Nickel Silver) but many other symbols are used: 1  EPBM (Electro Plated Britannia Metal). 2  EPCA (Electro Plated Copper Alloy). 3  ESM (Electro Plated Silver Mounts).he most common is EPNS (Electro Plated Nickel Silver) but many other symbols are used: 1  EPBM (Electro Plated Britannia Metal). 2  EPCA (Electro Plated Copper Alloy). 3  ESM (Electro Plated Silver Mounts).
The âNâ stands for âNegativeâ and the âPâ stands for âPositiveâ. With respect to sensors, an NPN device is one that can switch the negative side of the circuit while a PNP device switches the positive side.PN and PNP are technical terms for the type of transistor used to switch the output. The type of transistor determines the direction of current flow. For additional information about NPN-PNP devices, connections, and working with PLCâs check out the following from the Industrial Electrical and Maintenance forum.