Products 
Measuring and monitoring relays Voltage relays
Voltage relays
Voltage relay for AC, 3/N AC and DC systems
Depending on their technical design, voltage relays are used for monitoring voltages in single and three phase systems with direct and alternating voltage.
| VME420 | |
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The voltage relays of the VME420 series are designed to monitor the frequency, undervoltage, 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. |
| VME421H | |
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The voltage relays of the VME421H series are designed to monitor the frequency, undervoltage, 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. |
| VMD420 | |
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The multi-functional voltage relays of the VMD420 series are designed to monitor the frequency, undervoltage and overvoltage and the voltage between two threshold values (window discriminator function) 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 leading to the activation of the alarm relays will be stored. |
| VMD421H | |
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The multi-functional voltage relays of the VMD421H series are designed to monitor the frequency, undervoltage and overvoltage and the voltage between two threshold values (window discriminator function) 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 leading to the activation of the alarm relays will be stored. |
| VMD422 / VMD422H | |
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According to DIN V VDE V 0126-1-1, the voltage and frequency shall be monitored when feeding power into the public low voltage grid from decentralised power generation systems >30 kW (such as CHPs, wind, hydrodynamic and photovoltaic power plants). The three-phase voltage monitors of the VMD422 series continuously monitor the voltage and frequency at the transfer connection point in 3AC/3NAC systems and activate an alarm relay within 180 ms (response values according to VDEW guideline “Generator at the public low-voltage grid”) if voltage and frequency exceed upper and lower limits.An overvoltage (> U2), measured as average value over a 10-minute period, will cause the alarm relay to switch. The voltages are measured as r.m.s. values. In addition asymmetry, phase failure and phase sequence are monitored. |
| VMD423 / VMD423H | |
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According to DIN V VDE V 0126-1-1, the voltage and frequency shall be monitored when feeding power into the public low voltage grid from private electricity generation systems > 30 kW (such as CHPs, wind power stations, hydroelectric power plants and photovoltaic systems). The three-phase VMD423 series voltage and frequency monitors monitor the voltage and frequency at the feeding point of the public grid. At the feeding point of the medium voltage grid, the output voltages and frequencies are measured by means of voltage transformers (100 V). An alarm relay is activated within ≤ 80 ms when limit values are reached (response values according to VDEW guideline “Private electricity generation systems at the medium voltage grid”). An overvoltage (> U2), measured as average value over a 10-minute period, will cause the alarm relay to switch. |
| SUR353Z | |
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The relays of the SUR353Z series are designed to monitor the voltage of three-phase AC systems. Neutral conductor connection is not required, hence the relays are suitable for 3AC and 3NAC systems. External supply voltage is not required. |
| SUR357Z / SUR358Z | |
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The relays of the SUR357Z/358Z series are designed to monitor the voltage of three-phase AC systems. The relays can be used for both undervoltage and overvoltage monitoring (window function). Neutral conductor connection is not required, hence the relays are suitable for 3AC and 3NAC systems. Supply voltage and measuring voltage are galvanically separated. Special input transformers attenuate interferences from the system. The devices include an input circuit protection. |
| SUG140 | |
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The relays of the SUG140 series monitor the undervoltage in a DC system. External supply voltage is required. Response value, response delay, and hysteresis are adjustable. |
| SUG141 | |
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The relays of the SUG141 series are designed to monitor the overvoltage in a DC system. External supply voltage is required. Response value, response delay and hysteresis are adjustable. |
