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Overview Relays

General Information on Relays

There are numerous applications for relays in Telemetering Technique. They are necessary for the conversion of pulses from one form into another (e.g. S0 into bipolar current), for multiplying individual pulses and distributing them to multiple receivers (customer / public utility company) or for pulse value modulation (150 pulses / kWh to 100 pulses / kWh). Some of our relays offer all three applications combined into one unit.

Note: Ordering of HG components only on former explicit request.

Available Housing Types
The first three characters of the relay name provide information on the type of housing used for that relay. The practical differences are as follows:


Smallest housing type, for top hat rail installation (according to DIN EN 50022) of the more simple relays such as control relays.
2NW 18mm 90mm  60mm (W H D)
4NW 36mm 90mm  60mm (W H D)


Only on request!

Special housing for wall installation, or for installation direct on the terminal block of the meter.
Dimensions: 110mm 262mm 90mm (W H D)


Compact housing for wall or top hat rail installation. 10 connection terminals provide place for simple conversion, value modulation and multiplication relays.
Dimensions: 45mm 76mm 96mm (W H D)


For complex combinations of relays, providing up to 22 connection terminals. For wall or top hat rail installation.
Dimensions: 75mm 73mm 118mm (W H D)


Compact housing for wall or top hat rail installation (according to DIN EN 50022) with 16 connection terminals.
Dimensions: 75mm 76mm 116mm (W H D)


Special housing for top hat rail installation (according to DIN EN 50022). Types: ITR244, ITR220, ITR221.
Dimensions: 105mm 90mm 60mm (W H D)


Special housing for top hat rail installation (according to DIN EN 50022) with 24 connection terminals.
Dimensions: 40mm 79mm 107mm (W H D)


Relays for installation in 19"-system mounting racks or in wall mounted housings.
Types: ITR141 and ITR242


Survey of Products Relays as a PDF File
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Selection Help
Inputs / Transmission Distance

The S0-interface is relatively unproblematic and meant for shorter distances (up to 10m). S0 inputs are active elements. They supply the pulse detector with a signal, but also with an auxiliary power supply (our relais use ca. 12VDC). S0 elements can contain a complete electronic package without the complication of an extra power supply connection. The S0 specifications comply with DIN 43864 current and voltage limits.
Longer distances (up to 100m) are better bridged with wipe pulse- (115VAC or 230VAC) or bipolar current relays for some km ( 24VDC)

Auxiliary Power Supply

If an auxiliary power supply is available, then it is best to use relays with wear-resistant electronic contacts.. Relays that do not use an auxiliary power supply have limited uses (passive wipe pulses- and outputs or bipolar current with doubling of the interpreted value) and only allow for low pulse frequencies (up to about 5Hz).

Type of Construction

The 7PA... relays are recommended if wall or top hat rail installation is possible. They are both compact and relatively inexpensive and usually provide the most practical alternative.


The best results are provided with wear-resistant electronic contacts, but they are only available as make contacts at the present time. Our electronic wipe pulse outputs behave similarly to relay contacts, meaning that they can carry any kind of current up to a maximum of 265VAC/DC with 100mA. If double-throw contacts are required, then the mercury-wetted reed contacts provide the only alternative. These contacts are increasingly disapproved of, because of the negative environmental impact.

Galvanic Isolation

If the outputs have to be isolated from each other (e.g. to prevent problems from the customer side from traveling to the public utility net), then wipe pulse outputs should be selected. Relays with bipolar current outputs normally have only one power supply, meaning that the outputs cannot be isolated from each other.

Pulse Frequency

All relay types can be used up to about 5Hz. For higher frequencies the electronic relays with S0 inputs, and wipe pulse or bipolar current outputs should be used. Bipolar current inputs internally produce a 90ms pulse with every pole change and, because of this, must be specially made with a shortened pulse length if they are to be used here. Wipe pulse inputs must be excluded here, because of the long debounce time required when alternating current is used.

Pulse Gear (Pulse Value Modulator)

The values of pulses can be changed using a pulse value modulator.

Example: A meter delivers 75 pulses per kWh. Each pulse is evaluated as 0.01333 kWh. When a relay with a pulse value modulator is added, then the resulting pulses can be given values of e.g. 0.01 kWh, which can be processed by adding simple tariff units to the system.

Pulse values can be set directly on our tariff units, making pulse value modulators unnecessary.

At the link you are find a brief description and some examples for calculation and adjustment.

Pulse Timer

Some relays have built-in "Timers", that make the output pulse length independent of the input pulse length.

They typically produce 90ms pulses, which is important when the 5Hz-Technic is used. Other pulse values are available upon request.

    2NW / 4NW
  7PW / RWD

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Last Update 28.03.2019 at 14:51:35.