Control voltage circuits must be monitored for electrical safety; after all, an undetected electrical fault is as significant as unexpected system downtime and also significantly increases the fire risk. At the same time, unplanned service interventions can be expensive and time-consuming. Some transformer station insurers also demand effective condition monitoring systems. The Bender condition monitoring system gives you a clear overview of all the relevant data for your system.
The VMD258 analog voltage relay monitors three-phase AC systems for under and overvoltage (window function). It does not need a neutral point connection and is therefore suitable for all 3AC systems. The supply voltage of the electronics is taken from the system to be monitored. The supply for the electronics, the relays and the connection for the external energy store are separated from the system with dual insulation. Special input transformers muffle the transfer of interference factors from the system. The response values for under and overvoltage and for response delays can be adjusted to any level.
| Name | Category | Size | Language | Timestamp | D-/B-Number |
|---|---|---|---|---|---|
| EDS309x | Datasheets | 10.4 MB | EN | 2025/06/2424.06.2025 | D00012 |
| Power Quality/Measuring and monitoring relays | Product Overviews | 2.7 MB | EN | 2022/05/2525.05.2022 | |
| Product Overview ISOMETER®/ISOSCAN® | Product Overviews | 5.3 MB | EN | 2024/02/1616.02.2024 | |
| Product Overview - Residual Current Monitoring | Product Overviews | 8.0 MB | EN | 2025/04/0202.04.2025 | |
| Power Quality | Flyers | 468.0 KB | EN | 2022/12/1414.12.2022 | |
| Insulation Fault Location - Planning and Setup | Technical Article | 112.4 KB | EN | 2019/05/1313.05.2019 | |
| Where Residual Current Technology Meets the IT System | Technical Article | 353.8 KB | EN | 2019/05/1313.05.2019 | |
| Electrical Safety in Control and Auxiliary Circuits | Technical Article | 632.6 KB | EN | 2023/04/2121.04.2023 |
Products
Undervoltage/overvoltage relay for monitoring three-phase AC systems (window discriminator function)
Ground-fault detector for ungrounded AC/DC systems
Ground-fault monitoring device for ungrounded AC/DC control circuits
Ground-fault location module for ungrounded AC/DC systems
Ground-fault locator for localization of ground faults in control circuits
Portable ground-fault location systems for ungrounded and grounded systems
Ground-fault locator with 6 integrated measuring current transformers for localization of ground faults in main circuits
Ground-fault locator with 6 integrated measuring current transformers for localization of ground faults in control circuits
Multi-channel AC/DC ground-fault monitor
Multichannel AC, pulsed DC and AC/DC sensitive ground-fault monitor
Multi-channel AC/DC ground-fault monitor with individual relay outputs
Multichannel AC, pulsed DC and AC/DC sensitive ground-fault monitor with one alarm contact per channel
Universal measuring device with numerous measured quantities, energy and power measurement with storage, Power Quality Monitoring, limit value monitoring with alarm forwarding
AC/DC sensitive measuring current transformer (Type B)
Undervoltage/overvoltage relay for monitoring three-phase AC systems (window discriminator function)
Ground-fault detector for ungrounded AC/DC systems
Ground-fault monitoring device for ungrounded AC/DC control circuits
Ground-fault location module for ungrounded AC/DC systems
Ground-fault locator for localization of ground faults in control circuits
Portable ground-fault location systems for ungrounded and grounded systems
Ground-fault locator with 6 integrated measuring current transformers for localization of ground faults in main circuits
Ground-fault locator with 6 integrated measuring current transformers for localization of ground faults in control circuits
Multi-channel AC/DC ground-fault monitor
Multichannel AC, pulsed DC and AC/DC sensitive ground-fault monitor
Multi-channel AC/DC ground-fault monitor with individual relay outputs
Multichannel AC, pulsed DC and AC/DC sensitive ground-fault monitor with one alarm contact per channel
Universal measuring device with numerous measured quantities, energy and power measurement with storage, Power Quality Monitoring, limit value monitoring with alarm forwarding
AC/DC sensitive measuring current transformer (Type B)
Messrelais und Schutzeinrichtungen - Teil 1: Allgemeine Anforderungen
Messrelais und Schutzeinrichtungen - Teil 127: Funktionsnorm für Über-/Unterspannungsschutz
Elektrische Sicherheit in Niederspannungsnetzen bis AC 1 000 V und DC 1 500 V – Geräte zum Prüfen, Messen oder Überwachen von Schutzmaßnahmen - Teil 8: Isolationsüberwachungsgeräte für IT-Systeme
Elektrische Sicherheit in Niederspannungsnetzen bis AC 1 000 V und DC 1 500 V – Geräte zum Prüfen, Messen oder Überwachen von Schutzmaßnahmen - Teil 9: Einrichtungen zur Isolationsfehlersuche in IT-Systemen
Elektrische Sicherheit in Niederspannungsnetzen bis 1000 V AC und 1500 V DC - Geräte zum Prüfen, Messen oder Steuern von Schutzsystemen - Teil 15: Anforderungen an die funktionale Sicherheit von Isolationssteuergeräten in IT-Systemen und Geräten zur Erkennung von Isolationsfehlern in IT-Systemen
Safety requirements for secondary batteries and battery installations - Part 2: Stationary batteries
