Product Description

🔹 Digital Overvoltage and Undervoltage Line Monitoring Relay, 3-Phase Self-Powered – 7UG0818-1CA20

Product Description

The Siemens 7UG0818-1CA20 is a SIRIUS digital line monitoring relay designed for monitoring three-phase electrical networks in 3-phase 3-wire and 3-phase 4-wire configurations. It monitors important electrical parameters including phase failure, phase sequence, voltage and frequency conditions, helping detect abnormal power-supply conditions in industrial electrical systems. Siemens specifies an operating range of 280–500 V AC line-to-line and 160–300 V AC line-to-neutral for the applicable network configurations.

The relay is self-powered from the monitored supply, eliminating the need for a separate external control supply. It provides 2 changeover (2 CO) relay outputs that can be integrated into alarm, contactor-control and protection circuits. The compact 35 mm module design makes the device suitable for space-efficient installation in electrical control panels and automation systems.

The 7UG0818-1CA20 supports monitoring functions such as under-voltage, over-voltage, under-frequency, over-frequency, phase failure, phase sequence reversal and phase asymmetry, depending on the selected configuration. Programmable trip and recovery delays allow the relay to be adapted to different electrical system requirements.

Key Features

• Brand: Siemens

• Product Family: SIRIUS 7UG

• Part Number: 7UG0818-1CA20

• Product Type: Digital Line Monitoring Relay

• Network: 3-Phase 3-Wire / 3-Phase 4-Wire

• Operating Voltage: 280–500 V AC (L-L)

• Operating Voltage: 160–300 V AC (L-N)

• Control Supply: Built-in / Self-Powered

• Output: 2 CO

• Output Contacts: 2 Changeover Contacts

• Module Width: 35 mm

• Monitoring: Under Voltage

• Monitoring: Over Voltage

• Monitoring: Under Frequency

• Monitoring: Over Frequency

• Monitoring: Phase Failure

• Monitoring: Phase Sequence Reversal

• Monitoring: Phase Asymmetry

• Trip Time Delay: Programmable

• Recovery Time: Programmable

• Mounting: Electrical Control Panel / DIN-Rail Application

• Product Series: Siemens SIRIUS 7UG Monitoring Relays

Applications

The Siemens 7UG0818-1CA20 digital line monitoring relay is suitable for:

• Three-phase power supply monitoring

• Industrial electrical panels

• Motor control panels

• MCC panels

• Industrial automation systems

• Machine control cabinets

• Power distribution systems

• Motor feeders

• Pump control panels

• Compressor control systems

• HVAC electrical systems

• Industrial machinery

• Factory automation

• Generator monitoring applications

• Transformer secondary monitoring

• Electrical equipment protection

• Control and alarm systems

• Industrial power-quality supervision

Benefits

• Digital three-phase line monitoring

• Supports 3-phase 3-wire systems

• Supports 3-phase 4-wire systems

• Wide 280–500 V AC L-L operating range

• 160–300 V AC L-N operating range

• Built-in control supply

• No separate auxiliary supply required

• Two changeover relay outputs

• Phase failure detection

• Phase sequence reversal detection

• Phase asymmetry monitoring

• Under-voltage monitoring

• Over-voltage monitoring

• Under-frequency monitoring

• Over-frequency monitoring

• Programmable trip delay

• Programmable recovery delay

• Compact 35 mm module design

• Suitable for industrial automation and control applications

High-Level SEO Keywords

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Frequently Asked Questions

Q1. What is Siemens 7UG0818-1CA20?
The 7UG0818-1CA20 is a Siemens SIRIUS digital line monitoring relay designed for monitoring three-phase electrical networks.

Q2. Which electrical systems does 7UG0818-1CA20 support?
It supports 3-phase 3-wire and 3-phase 4-wire network configurations.

Q3. What is the operating voltage range?
The specified operating range is 280–500 V AC line-to-line and 160–300 V AC line-to-neutral, depending on the network configuration.

Q4. Does the relay require a separate control supply?
No. The relay has a built-in control supply and is powered from the monitored network.

Q5. How many output contacts does it provide?
The relay provides 2 changeover contacts (2 CO).

Q6. What faults can the relay monitor?
It can monitor conditions including under-voltage, over-voltage, under-frequency, over-frequency, phase failure, phase sequence reversal and phase asymmetry.

Q7. What is the module width?
The 7UG0818-1CA20 is available in a compact 35 mm module format, making it suitable for space-efficient control-panel installations.

Q8. Can it monitor phase sequence reversal?
Yes. Phase sequence reversal is one of the line-monitoring functions supported by the relay.

Q9. Where is Siemens 7UG0818-1CA20 commonly used?
It is suitable for MCC panels, motor control panels, industrial automation, machine control cabinets, power distribution systems, pumps, compressors and industrial machinery.

Q10. Does 7UG0818-1CA20 have neutral-loss protection?
Siemens' current comparison documentation lists neutral-loss protection under 7UG0814-1CA20, not 7UG0818-1CA20. Therefore, for product-page accuracy, 7UG0814-1CA20 should be used when neutral-loss protection is specifically required.