General
Waveform	IT system (without neutral conductor)
Operating voltage	400 VAC
Voltage tolerance	±10%
Frequency	50/60 Hz
Frequency tolerance	±5%
Response delay	<0,4 s
Trigger threshold	<1000 Ω
Power loss	23 VA
Degree of protection terminals	IP20
Degree of protection housing	IP40
Alarm contact	max. 250 VAC/5 A; 30 VDC/2 A
Ambient temperature operation	−15 to +40 °C
Storage ambient temperature	-25 to +70 °C
Mounting	DIN rail TS35 (DIN EN 50022)
Solid connection	max. 4.0 mm²
Flexible connection	max. 2.5 mm²
Approvals	CE
Standards	DIN EN 50178 / VDE 0160; DIN EN 61800-5-1

The protective earth conductor monitoring device from EPA, manufacturer's number 50275391, is a specialized device for monitoring the protective earth conductor (PE) in 3-phase IT networks, i.e., networks without a neutral conductor. It is designed for continuous monitoring of leakage currents in the protective earth conductor to enable early detection of insulation faults or other disturbances in the electrical system. The device is specifically designed for installations with frequency converters in IT networks, where stable and secure power supply is of high importance. Monitoring is carried out in accordance with standards DIN EN 50178/VDE 0160 and DIN EN 61800-5-1, which apply to safety and functionality in industrial and technical installations.

Applications
This device is designed for use in industrial and technical installations where IT networks are employed, for example in production facilities, machine building, or installations with frequency converters. IT networks are particularly common in manufacturing technology, as they offer high operational safety, since an insulation fault does not cause a short-circuit current but only a small leakage current. The monitoring device ensures that this leakage current in the PE conductor is continuously monitored, triggering an alarm message if the threshold is exceeded.

Functions and Equipment in Detail
The device features an alarm relay that closes a contact when a fault is detected in the protective earth conductor or in a network phase. This contact can be connected to external warning systems, such as light or sound signals. The status indication is provided by an LED display, signaling three states: OK (normal operating conditions), Fault Network Phase (disturbance in one of the network phases), and Alarm (threshold exceeded in the PE conductor). An integrated test button allows manual verification of the device's functionality. Optionally, an external test button can be connected, facilitating integration into larger monitoring systems.

Technology Explained Simply
The device's threshold is below 1000 Ω, meaning it reacts when the resistance in the protective earth conductor is below this value. The response delay is less than 0.4 seconds, enabling a rapid reaction to disturbances. The operating voltage is 400 VAC with a tolerance of ±10 %, and the frequency is 50/60 Hz with a tolerance of ±5 %. The device's power consumption is 23 VA, which is relevant for operational safety and heat generation. The protection rating is IP20 at the terminals and IP40 at the housing, protecting against finger contact and against entry of solid foreign objects larger than 1 mm, as well as against splashing water directed toward the terminals, but not against direct water jets. The device is designed for indoor use, as the IP40 rating does not ensure suitability for outdoor environments.

Compatibility and Accessories
The device is designed for installations with frequency converters in IT networks, representing a specific application in industrial automation and machine control. The connection cross-sections are limited to max. 4.0 mm² solid and max. 2.5 mm² flexible with ferrule, enabling use with standard cables. Mounting is done on a TS35 support rail in accordance with DIN EN 50022, allowing installation in standard switchboards or distribution boxes. The operating ambient temperature ranges from −15 °C to +40 °C, while the device can withstand storage temperatures from −25 °C to +70 °C.

Mounting and Installation
Mounting is done on a TS35 support rail, commonly used in electrical engineering for switchboards and distributors. The terminals are designed for the specified cross-sections, with flexible cable only allowed to be connected using a ferrule. Installation is typically carried out in the distribution board or near the main supply to ensure rapid response to disturbances. Connection cables must be routed in accordance with regulations for electrical installations.

Advantages in Operation
Continuous monitoring of the protective earth conductor enables early detection of insulation faults, increasing operational safety and preventing damage to machines or installations. The clear LED display and alarm relay ensure quick and unambiguous notification of faults. Integration into existing monitoring systems via external test button and alarm contact enables centralized fault diagnosis. The device is optimized for use in IT networks, which play an important role in industrial electrical engineering.