For regulating road tunnel lighting.
The Hitachi EH-150 PLC has been provided with a specially designed program for regulating road tunnel lighting.
The PLC receives a 4-20 mA signal from a Hagner TLS-420 Tunnel Photometer (where 4 mA = 0 cd/m² and 20 mA = the chosen calibration level, e.g. 6,500 cd/m²).
The PLC has been programmed to activate built-in relay switches at certain current levels (up to 10 levels set according to the customer's requirements). Programmed time delays mean that a switch is only activated when the signal has been steady over or under the level in question for a certain time. The relay switches can then be connected to contactors which regulate the lighting inside the tunnel.
The preset switching levels and time delays can easily be changed by the customer by means of a display unit, which normally is ordered with the PLC.
Each PLC can in standard version be used with 2 separate Tunnel Photometers.
For more information contact B.Hagner AB