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Secure drive systems sensorless

Safe frequency monitor now also with UL apporval


Speed and Frequency monitor UH 6937


Ensure high security for an economical price, the speed and frequency monitor UH 6937 from the SAFEMASTER S series opens up new possibilities in machine safety for construction, planning, and retrofitting, for instance in wood machining or for tooling machines.


Monitoring the output frequency of drive inverters is just one of its many uses. In case of over- or under-frequency, or if the frequency falls outside the set window, the frequency monitor will securely switch off, preventing any hazardous situations. A broad spectrum of AC voltages for which frequency is a key safety criteria for application can be monitored.


Depending on the machine's operating mode, one of the maximum of four pre-configured parameter sets can be securely selected using input terminals. In automatic mode, this can, for instance, prevent excessive speeds that would lead to a dangerous situation, and might even result in a total machine failure. In set-up mode, the machinist does not need to completely switch off the machine, but can instead operate at reduced speed to minimize the risk and make processes more efficient. This allows the frequency monitor to increase worker safety and machine efficiency.


Redundant, positively guided relay contacts securely switch off in applications up to PL e / Cat. 4, SIL 3. A muting function and analog output for further processing of the measured frequency complete this easy-to-handle device.


A user-friendly menu structure on a lit display can be used to change settings, and shows the current status and measured frequency at all times during operation.


The frequency monitor is approved for use in drive technology in accordance with EN 61800-5-2, as well as in process industry applications pursuant to EN 61511.