Page 3 - Doepke_5961002_diz202404_dig_en

No 4 | November 2024 DIZ | DoePke-INfo-ZeItuNg ––– Page 3

Residual current protection for heat pumps

As winter beckons, many people are starting ---------- the regional energy supplier requires the environment in which it is installed. Heat
to think about their heating. According to the the use of a residual current device pumps are usually located outside and are often
Federal Association of the German Energy exposed to harsh or unknown environmental
and Water Industries (BDEW), one in every ---------- the heat pump is installed in an operating conditions. If there is even the slightest pos-
three heating systems in Germany is more than site at risk of fire sibility that an overcurrent protective device
20 years old. It is no wonder that, given the cannot achieve the required switch-off times in
sky-rocketing oil and gas prices that we have ---------- the heat pump is installed in an agricul- the event of an earth fault, heat pump manu-
also been contending with, many people are tural facility facturers will not take any risks. In addition to
now opting for a heat pump. Although heat raising the general level of protection, warranty
pumps currently make up just 5.7 per cent of ---------- the responsible electrician recommends issues also come into play.
the heating technologies used, their share has the use of a residual current device after
more than doubled since 2019 (when it was assessing the conditions. Since heat pumps use frequency converters
2.2 per cent). In new builds, the share of heat which can generate smooth DC residual
pumps was already 57 per cent by 2022. currents, most manufacturers prescribe the use
of AC-DC sensitive residual current devices.
The rise of sustainable technologies also calls In this case, Type A RCDs may not be used.
for new strategies for ensuring they are safe. If a Type A device is already present, it must
But what is the ideal way to protect against be replaced. However, if a heat pump is being
dangerous residual currents in a heat pump? integrated into an existing installation, it is
Is a residual current circuit-breaker necessary, important to check whether lines need to be
and if so, what kind? replaced due to a change in operating condi-
tions, for example continuous duty or larger
In some cases, the regulatory standards are operating currents.
unambiguous: for final circuits with sockets
and in TT power supply systems, a residual The DFS HP (HP for ‘heat pump’) was specially
current circuit-breaker must be installed. If it developed for use in systems with heat pumps
is possible for smooth DC residual currents to and offers the optimum protection parameters
occur in the event of a fault, the circuit-breaker for them.
must be AC-DC sensitive.
It is AC-DC sensitive and the level of protec-
As far as the relevant standards are concerned, tion satisfies all the requirements of the heat
an overcurrent protective device is generally pump manufacturers. What’s more, with the
sufficient for TN systems. A residual current Another decisive reason for using a residual short delay optimised for heat pumps, system
circuit-breaker is usually only prescribed by current device is if this is recommended or availability is increased. This means the heat
the standards if... pump continues running even in the event of
even required by the heat pump manufacturer. pulse shaped surge currents. False tripping due
These days, most manufacturers make such a
---------- the responsible insurance company recommendation, because a residual current to switching operations or lightning strikes is
virtually eliminated.
requires the use of a residual current device may be necessary not only due to the
device for fire protection reasons nature of the heat pump itself, but also due to
And for use in harsh environments, the
DFS HP is also available in a heavy-duty (HD)
version. This version is particularly resistant to
dust, corrosive gases, heat and cold.

akademie.doepke.de The DFS HP is available with a rated residual
current of 30 mA, 100 mA and 300 mA.

Doepke Academy – dates for 2025
Doepke A cademy 16/01/2025 Maximum listening enjoyment: DFS Audio

23/01/2025 Doepke meets Fluke
20/03/2025 Doepke talk – building type E
15/05/2025 Mobile safety: DPRCD
Online Seminars 26/06/2025 Intelligent residual current
monitoring with e.Guard

04/09/2025 Doepke talk