Metrix 450 Economical Switch
The electronic switch utilizes a solid state crystal accelerometer which provides an electrical output when it is deformed by the vibration forces. The output is electronically converted to a signal proportional to velocity. This signal is compared with a preset limit and triggers a solid state relay if the limit is exceeded. There are no moving parts in the 440 vibration switches except when configured with mechanical relays.
An important feature of the switch is the built-in time delay. This prevents triggering of the alarm or shutdown functions from transient increases in vibration levels. It also avoids shutdown due to transitory vibrations occurring during start-up.Almost all machines experience a few seconds of high vibration during start-up before reaching operating speed. When no time delay function is included, as with mechanical switches, this start-up vibration causes a trip. Frequently, the operator turns the trip setting up until he can get through start-up. The resultant trip level is too high to
afford protection at the machine’s operating speed.
Three-second alarm trip delay is standard on the switch. Alarm time delays are independently adjustable in the field over a range of 2 to 15 seconds.Product Aprox. Weight: 2.7 kg (6 lbs)
- Shutdown and alarm settings are based on vibration severity. The internal sensor (unless the external sensor option has been specified (Ordering Option I=5 – see note in Section 5.4) is a piezoelectric crystal with built in microelectronics to reduce noise sensitivity. The output signal is electronically integrated to measure and trip on velocity
- Calibrated setpoint controls permit set point adjustment of vibration velocity levels up to full scale range. DR model switches have dual setpoints – one for alarm and one for shutdown – that are independently adjustable.
- 4-20 mA output provides a convenient interface for trending and displaying vibration amplitude in a programmable logic controller (PLC), SCADA system, data logger, or other instrumentation. 4mA corresponds to no vibration, and allows the user to distinguish between no power to the switch (0mA) and a functional switch but with no vibration present (4mA). 20mA corresponds to full scale vibration amplitude.
- Discrete outputs used for alarming and shutdown can be selected from triac, solid-state analog switch (FET), or electromechanical relays, but must be specified at time of ordering. These outputs are independently configurable for open on alarm/shutdown or close on alarm/shutdown .
- An adjustable (2-15 seconds) time delay is standard. This prevents false alarms/shut-downs on high startup vibrations and also from non repetitive transient events.
- Self-test and verification: An LED adjacent to each setpoint control illuminates the instant the measured vibration level exceeds the setpoint. The unit can be periodically verified on line by turning the setpoint control down until the LED comes on. This setting is then compared with the vibration amplitude measured via a portable vibration meter at the same location as the switch’s sensing element, providing a verification check of the unit.