E. Dold & Söhne GmbH & Co. KG

Tel.: +49 7723 654-0
E-Mail: dold-relays@dold.com

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Tel.: +49 7723 654-454
E-Mail: ab@dold.com

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E-Mail: rv@dold.com

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MK 9055N

Speed Monitor

MK 9055N


Auxiliary voltage

Response value

Terminal type

Approvals and Markings


  • 0058715
  • MK9055N.12 1-120000IPM AC230V+DC24V
The speed monitors MK 9055N and MH 9055 monitors the rotational speed of motors. They recognise... more

Product description

The speed monitors MK 9055N and MH 9055 monitors the rotational speed of motors. They recognise and monitor impulse signals of e. g. proximity sensors and protect machines and produced material or allows speed depending switching in production processes.

Technical specifications

Width: 22,5 mm
Measuring range max.: 120000 IPM
Auxiliary voltage: AC, DC
Classification: Drehzahlüberwachung
Output contacts: 2 C/O contacts
Enclosure design: Switch cabinet
Type: MK 9055N


  • Protection of persons, machines and products
  • Easy setting
  • Universal input, for configuration of different sensors (PNP, NPN, 2-wire, contact, voltage)
  • With fast reaction at low speed


  • According to IEC/EN 60255-1
  • Detection of high or low-rpm / stand still (adjustable function)
  • Large setting range 1 ... 120.000 IPM or 0.15 ... 20.000 Hz (10 ranges each)
  • As option with input for NAMUR-sensors with sensor and wire protection against interruption and short circuit
  • Adjustable hysteresis 0.5 ... 50 %
  • Adjustable start up time delay 0 ... 50 s, control with external contact
  • Adjustable monitoring time for missing input signal at function overfrequency; additional using as standstill level
  • Programmable via termminals:
    - Alarm delay of 0 ... 100 s
    - with manual reset or auto reset
  • LED-indication for auxiliary voltage, measuring input and output relay; additional LED for indication of wire- / sensor failure at NAMUR-input
  • Auxiliary voltages AC 230 V and DC 24 V in one unit
  • 2 changeover contacts, closed circuit operation
  • Open circuit operation on request
  • As option with analogue output, proportionally to speed
  • Device available with 2 response values and seperately controlled output relays for under- and overfrequency see MK 9055N/5_ _
  • MH 9055 with wide input range for auxiliary voltage (AC/DC 24 ...60 V or AC/DC 110 ...230 V)
  • 2 possible compact designs
    MK 9055N: Width 22,5 mm
    MH 9055: Width 45 mm