monitoring relays. VME420 Datasheet
Bender Incorporated • 700 Fox Chase, Coatesville PA 19320 • Tel.: (800) 356-4266 • Fax: (610) 383-7100
Multi-functional monitoring relays for overvoltage,
undervoltage and frequency monitoring
in AC/DC systems with external supply voltage
The voltage relays of the VME420 series are designed to monitor the frequency, under-
voltage, overvoltage and the voltage between two threshold values (window discriminator
function) in AC and DC systems. The voltages are measured as r.m.s. values. The currently
measured value is continuously shown on the LC display. The measured value leading to the
activation of the alarm relays will be stored. Due to adjustable response times, installation-
specific characteristics, such as device-specific start-up procedures, short-time voltage
fluctuations, etc. can be considered . Device version VME420 requires an external supply
• Monitoring AC/DC systems for under-
voltage, overvoltage and frequency in
the voltage range of 0…300 V
• Different monitoring functions selectable
< U, > U or < U/> U, < f, > f or < f / > f
• Start-up delay, response delay, delay
• Adjustable switching hysteresis
• r.m.s. value measurement (AC + DC)
• Digital measured value display via
multi-functional LC display
• Preset function (automatic assignment
of basic parameters)
• LEDs: Power On, Alarm 1, Alarm 2
• Measured value memory for operating
• Continuous self monitoring
• I nternal test/reset button
• Two separate alarm relays
(gold-plated relay contacts),
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)
• Indication of the system frequency
• RoHS- compliant
• Single -phase voltage and frequency monitoring of machines and electrical installations
• Earth fault monitoring in medium-voltage systems via voltage transformers
• Monitoring of battery systems
• Switching on and switching off at a certain voltage level
Once the supply voltage is applied, the start-up delay “t” is activated. Measured voltage
and frequency values changing during this time do not influenc e the switching state of
the alarm relays.
The devices provide two separately adjustable measuring channels (overvoltage/under-
voltage). When the measuring quantity exceeds the response value (Alarm 1) or falls
below the response value (Alarm 2), the time of the r esponse delays “ton 1/2” begins.
Once the response delay has elapsed, the alarm relays switch and the alarm LEDs light.
When the measuring value exceeds or falls below the release value (response value plus
hysteresis) after the alarm relays have switched, the selected release delay “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 the alarm state 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.
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 under-
frequency 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 key is pressed, a nominal system voltage is being searched cyclically
(PrE run). If a key 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
24 Main catalogue part 3 – 06.2007 / Electronic measuring and monitoring relays
Right to modifications reserved ! – © Dipl.-Ing. W. Bender GmbH & Co. KG, Germany
Monitoring relays for overvoltage, undervoltage and frequency monitoring VME420
1 - LED Power On “ON” (green); lights when supply voltage is
applied and flashes in the event of system fault alarm.
2 - Alarm LED “AL1” (yellow), lights when the set response value
> U / < f / > f is ex ceeded and flashes in the event of system
3 - Alarm LED “AL2” (yellow), lights when the value falls belo w
the set response value< U / < f / > f and flashes in the ev ent
system fault alarm.
4 - Multi-func tional LC display.
5 - Test button “T”: UP key: To change the measured value
display, move downwards in the menu or
To call up the self test: Press the key > 1.5 s
6 - Reset “R” button: DOWN key: To change the measured value
display, move downwards in the menu or
Delete stored alarms: Press the key > 1.5 s
7 - MENU key:
Enter key: To confirm the measured value
display or change parameters.
To call up the menu ssytem : Press the key> 1.5 s
Press ESC key > 1.5 s: t o abort an action or to
return to the previous menu level.
1 - Connection to the system/load being monitored
2 - Supply voltage US (see ordering information)
3 - Alarm relay K1: Configurable f < U / > U / < f / > f / ERROR
4 - Alarm relay K2: Configurable f < U / > U / < f / > f / ERROR
5 - Line protection according to IEC 60364-4-43
A 6 A fuse is recommended. If being supplied from an
IT system, both lines have to be protected by a fuse.
Main catalogue part 3 – 06.2007 / Electronic measuring and monitoring relays 25