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VMD420


LINETRAXX® VMD420
Multi-functional voltage relay for 3(N)AC systems,
frequency/overvoltage/undervoltage, phase, phase failure, asymmetry

 

BENDER three phase AC under/over voltage relay VMD420

Product description:

The multi-functional VMD420 series voltage relay is designed to monitor the frequency, undervoltage and overvoltage and the voltage between two threshold values in 3(N)AC systems. The voltages are measured as r.m.s. values. The currently measured value is continuously shown on the LC display. The measured value required to trigger the alarm relay is stored. Due to adjustable response times, installation-specific characteristics, such as device-specific start-up procedures, short-time voltage fluctuations, etc. can be considered.
The devices require an external supply voltage.


Device features:

• Undervoltage, overvoltage and frequency monitoring in 3(N)AC systems 0…500 V
• Asymmetry, phase failure and phase sequence monitoring
• Various monitoring functions selectable < U, > U, < f, > f
• Start-up delay, response delay and delay on release
• Adjustable switching hysteresis
• r.m.s. value measurement (AC+DC)
• Digital measured value display via multi-functional LC display
• Preset function (automatic setting of basic parameters)
• LEDs: Power On, Alarm 1, Alarm 2
• Measured value memory for operating value
• Continuous self monitoring
• Internal test/reset button
• Two separate alarm relays (one changeover contact each)
• N/C or N/O operation and fault memory behaviour selectable
• Password protection for device setting
• Sealable transparent cover
• Two-module enclosure (36 mm)
• Push-wire terminal (two terminals per connection)
• RoHS compliant

Application:

• Monitoring of voltage-sensitive machines and electrical installations
• Switching machinery and equipment on and off at a certain voltage level
• Monitoring of stand-by and emergency supply systems
• Supply voltage monitoring of portable loads
• Protection of three-phase motors against phase failure and phase open-circuit
• Transformer protection, asymmetrical load can be recognised

Preset function:

Once the supply voltage is applied, the start-up delay “t” begins. Measured voltage and frequency values changing during this time do not influence the switching state of the alarm relays.
The devices feature two separately adjustable measuring channels (overvoltage/undervoltage).
When the measuring quantity exceeds the response value (“Alarm 1”) or falls below the response value (“Alarm 2”), the time of the response delays “ton1/2” begins.
Once the response delay has elapsed, the alarm relays switch and the alarm LEDs light up. When the measuring value exceeds or falls below the release value (response value plus hysteresis) after the alarm relays have switched, the selected release time “toff” begins.
When “toff” has elapsed, the alarm relays switch back to their initial position. When the fault memory is activated, the alarm relays remain in alarm position until the reset button “R” is pressed. When the fault memory is set to continuous mode, the alarm parameters remain stored, even on failure of the supply voltage.

Preset function:

After connecting the device for the first time, the nominal system voltage will be determined (PrE run), and the response values for overvoltage and undervoltage as well as for underfrequency and overfrequency will automatically be set. When no voltage is determined within a nominal system voltage range (PrE run), the response values will be set to the minimum or maximum voltage. In this case, the message “AL not SET” appears on the display.
As long as no button is pressed, a nominal system voltage is being searched cyclically (PrE run). If a button is pressed, the search will be interrupted and the message “AL not SET” disappears. In this case, the appropriate response values have to be set in the menu.
When activating the frequency monitoring function, the preset frequency will automatically be stored.

Wiring diagram:

BENDER three phase AC under/over voltage relay VMD420 wiring diagram

Dimensions:

BENDER three phase AC under/over voltage relay VMD420 dimensions

Technical data:

BENDER three phase AC under/over voltage relay VMD420 technical data

Ordering information:

BENDER three phase AC under/over voltage relay VMD420 ordering information