Which isolating relays are recommended for the isolation of the RU signals?

If required, the RU will specify these relays. Installation to be carried out by the utility company or the customer at a charge.

If the customer sets the relays:

• Data sheet fiber optic isolating relay.pdf.

For your information, I have attached the data sheet of a fiber optic isolating relay (communication with the meter is serial via fiber optics, as already mentioned); this relay is now used by a large number of energy suppliers (by EMH, please enquire about project planning if necessary).

In cases where conventional isolating relays are still used, they are controlled by the meter via 100 V AC or 230 V AC signals. A common isolating relay would be the Deppe triple isolating relay ZMT 80-01.

The Siemens isolating relays you mentioned, 7FR50 66-... (58, 115, 230 V AC) are still known to me (they are still lying around from earlier projects), are suitable for every optimization system with regard to signal duration (at least 80 ms), but as far as I know they are almost no longer used.

The pulse acquisition of the U1500 is interrupt controlled; the operating system interrupts the program processing every millisecond, so that also very high pulse frequencies and very short signal durations can be acquired (thus all common isolating relays with MOSFET or relay outputs can be used with the U1500; the isolating relay to be used is usually specified by the power supplier; the installation is done by the power supplier or the customer's operating technology).

By default, all pulse inputs (maximum 16 per component) are debounced with 15 ms (longer or shorter debounce times are possible); the period signals are debounced with 500 ms (usual period signal lengths are 1 to 9 seconds) and the tariff switching signals in the seconds range.