RBM 50-30/15 400V/3 Duct heater with integral control equipment for rectangular ducts. Manufactured from Aluzinccoated sheet steel with a heating element in stainless steel. The heater has integral overheating protection with a manual reset function. The unit is controlled by an integral electronic temperature regulator, using so-called time-proportional Pulse/Pause technology. This provides extremely precise temperature control. As a thyristor is used for adjusting the temperature, the unit has no moving parts. This means that it is silent and not susceptible to wear and tear. The RBM is supplied with a complete and fully-connected control system including contactors and alarm relays. This minimises the installation cost. The external installation requirements are: mains power supply, control circuit, dial for setting required temperature, sensor and a possible alarm circuit. The minimum air volume is based on a minimum air velocity of 1.5 m/s. These duct heaters are designed for a maximum output air temperature of 40