• a.c., d.c. or a.c./d.c. main circuits.
• a.c./d.c. main circuits with directly connected DC components, such as rectifiers, converters, regulated drives.
• UPS systems, battery systems.
• Heaters with phase control.
• Systems including switch-mode power supplies.
• IT systems with high leakage capacitances.

A range of insulation monitoring devices in accordance with IEC 61557-8 for IT systems. The devices are universally applicable in a.c., 3(N) a.c., a.c./d.c. and d.c. systems.

a.c. systems may include extensive d.c.-supplied loads (such as rectifiers, inverters, variable-speed drives).

Insulation monitoring devices continuously monitor the insulation resistance of IT systems (unearthed systems) and issue an alarm if the value falls below a response value.

The iso685 series uses the patented AMP^Plus measurement method. This allows concise monitoring of modern power supply systems, also in case of extensive, directly connected DC components and high system leakage capacitances.

To obtain a measurement, the device has to be connected between the IT system and the protective earth conductor (PE). A measuring current is superimposed onto the system which is detected and evaluated by a measuring circuit. Insulation monitoring devices detect deteriorations of the insulation level at an early stage and in a reliable way.

Features and benefits:

Optimized maintenance:

• Early detection and reporting of insulation degradation.
• Automatic localisation of faulty current paths.
• Optimized use of time and personnel resources.
• Centralized information about the installation status.
• Remote diagnosis via Internet/ Ethernet.

Increased fire protection:

• Early detection of gradually developing insulation faults.
• Minimizing fault arcs as a common cause of fire.
• Separating areas prone to explosions and fire from the rest of the system via isolating transformers and monitoring these areas separately.

Improved economic efficiency:

• Avoiding expensive and unplanned installation shutdowns.
• Reducing time and staff expenses for maintenance.
• Detecting weak points in installations.
• Support of investment decisions.

Increased operational reliability:

• No interruption to operation at the first fault.
• No control malfunction in the event of insulation faults.
• Electrical installations are kept at a high level of availability.
• Monitoring electrical installations and loads even when not in operation.

Enhanced accident prevention:

• Low touch currents in small-sized and medium-sized installations.
• No malfunction in control systems of installations and machines due to an earth fault.

Higher earthing resistances permissible, for example, for mobile power supplies.