The 6666 continually compares the value for each input channel to the user-defined Alert and Danger alarm setpoints. The 6667, which utilizes cold junction compensation required for thermocouples, continually compares the value for each input channel to the user-defined Alert and Danger alarm setpoints. The 6675 is a single channel rotation monitor used to provide continuous monitoring of rotating machinery speed as measured by a non-contact eddy current probe or a magnetic interrupter. Although the default configuration for the 6675 is a single channel monitor, it can be factory configured to accept a second, redundant input, which facilitates automatic switching to the second probe if the first probe fails. In addition to monitoring machine speed, the 6675 provides zero speed detection, locked rotor alarming and acceleration monitoring.
Locked rotor alarming provides monitoring of the startup sequence of large electric motors.
Zero speed detection is most commonly used in the operation of machines with high mass rotor systems, such as steam turbines, to detect when to engage the turning gear. The 6676 Single Channel Reverse Rotation Monitor provides reverse rotation detection and continuous monitoring of rotating machinery speed, measured by non-contact eddy current probes. This monitor utilizes two non-contact probes to monitor both speed and direction, and can detect speeds up to 50,000 rpm in the forward direction and 10,000 rpm in the reverse direction. This functionality is very useful in fan, boiler feed water pumps and small steam turbine applications, where any reverse direction of the machine can cause extensive damage. For example, in a boiler feed water pump application, where water is pumped up a vertical rise, the pump can actually reverse direction when shutdown, due to the back pressure from the water.