Isometer® iso685-d-p iso685W-d-p iso685-s-p iso685w-s-p insulation Monitoring Device with integrated locating current injector for it ac systems with galvanically connected rectifiers and inverters and for it dc systems
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- 3.2.2 Special characteristics of ISOMETER® iso685-S-P with front panel
- 3.3 Functional description
| 3.2 Product description
3.2.1 General product description The ISOMETER® is an insulation monitoring device in accordance with IEC 61557-8 and IEC 61557-9 for IT systems. It is universally applicable in AC, 3(N)AC, AC/DC and DC sys- tems. AC systems may include extensive DC-supplied loads (such as rectifiers, inverters, variable-speed drives). 3.2.2 Special characteristics of ISOMETER® iso685-S-P with front panel The ISOMETER® iso685-D-P and iso685W-D-P are devices of the iso685 device family with integrated display. This manual applies in full to these ISOMETER®s. The ISOMETER® iso685-S-P and iso685W-S-P are sensor variants of the iso685 device fam- ily without display. The only difference between these variants and the ISOMETER®s iso685-D-P and iso685W-D-P is that they do not feature a display. The ISOMETER®s iso685-S-P and iso685W-S-P must be used in combination with a front panel because the devices are operated via the front panel. The operation of the front panel is equal to the operation of the ISOMETER®s with integrated display, which is described in this manual. Only the sensor variant (ISOMETER® iso685-S-P or iso685W-S-P) can be connected to the front panel. Connection to the display variant (ISOMETER® iso685-D-P or iso685W-D-P) is not possible. Function Function iso685-D-P_D00170_03_M_XXEN/07.2017 13 Hereafter, the ISOMETER®s with integrated display are described. This description is sim- ilar to the combination of ISOMETER® sensor variants and the front panel FP200. The de- vices to which this manual applies will be referred to as ISOMETER®s hereafter. 3.3 Functional description The insulation monitoring device continuously monitors the entire insulation resistance of an IT system during operation and triggers an alarm when the value falls below a pre- set response value. To obtain a measurement, the device has to be connected between the IT system (unearthed system) and the protective earth conductor (PE). A measuring current in the µA range is superimposed onto the system which is recorded and evaluat- ed by a microcontrolled measuring circuit. The measuring time depends on the selected measurement profiles, the system leakage capacitance, the insulation resistance and possible system-related disturbances. The response values and other parameters are set using a commissioning wizard or via different setup menus using the device buttons and a high-resolution graphic LC display. The selected settings are stored in a permanent fail-safe memory. Different languages can be selected for the setup menus and the messages indicated on the display. The de- vice utilises a clock for storing fault messages and events in a history memory with time and date stamp. The settings can be protected against unauthorised modifications by a password. To ensure proper functioning of the connection monitoring, the system type 3AC, AC or DC must be set and the appropriate terminals L1/+, L2, L3/- must be connected. The ISOMETER® is able to measure the insulation resistance reliably and precisely in all common IT systems (unearthed systems). Due to various applications, system types, op- erating conditions, application of variable-speed drives, high system leakage capacitanc- es etc., the measurement technique must be able to meet varying requirements in order to ensure an optimised response time and an optimised relative uncertainty. Different measurement profiles which can be selected from a setup menu allow optimum adapta- tion of the measurement technique to the specific application. If the preset response value falls below the value of alarm 1 and/or alarm 2, the associated alarm relays switch, the LEDs ALARM 1 or ALARM 2 light and the measured value is shown on the LC display (in case of insulation faults in DC systems, a trend graph for the faulty conductor L+/L- is displayed). If the fault memory is activated, the fault message will be stored. Pressing the RESET button resets the insulation fault message, provided that the insulation resistance is at least 25 % above the preset response value. As additional Infor- mation, the quality of the measuring signal and the time required to update the meas- ured value are shown on the display. A poor signal quality (1-2 bars) may be an indication that the wrong measurement profile has been selected. The ISOMETER® has an internal system isolating switch, which makes it possible to oper- ate several ISOMETER®s in coupled IT systems. For this purpose, the ISOMETER®s are con- nected via an Ethernet bus. The integrated ISOnet function ensures that only one ISOMETER® is actively measuring at a time, while the other devices are completely isolat- ed from the system and waiting in standby mode for measuring permission. |