Global site

ABB's website uses cookies. By staying here you are agreeing to our use of cookies. Learn more

Frequently asked questions (FAQ)

Below you will find a list of frequently asked questions about H+Line.

TI - Is it possible to receive the test report related to the medical insulating transformer according to the IEC 60364-7-710 reference standard?

Certainly. It is enough to communicate the serial number printed on the label at the metallic base of the transformer, since the test reports on each produced unit are performed at the factory. The serial number is the seven digit number, as shown in the picture of the label below.


TI - How shall the PT100 temperature probes of the medical insulating transformer be connected?

The temperature probes shall be connected to ISOLTESTER-DIG insulation monitoring device, as follows:
- Connection of the primary winding temperature probe:


TI - Shall the insulating transformer be protected?

All transformers shall be protected from short circuits according to the IEC 60364-1 reference standard. The protection shall be assigned by the manufacturer in order to guarantee suitable coordination.

TI - Can the upstream protection of insulation transformer be performed with an overcurrent protection device?

In compliance with the instructions provided by the manufacturer, an overcurrent protection device can be therefore used to protect the upstream side of the insulation transformer. The 710.531 is satisfied if the rated current of the circuit breaker upstream is higher than the rated current of the transformer.


TI - Can I use any kind of insulating transformer in medical premises?

General purpose insulating transformers have to be used in accordance with the EN 61558-2-4 reference standard “Particular requirements for general insulating transformers”. The range of IT medical insulating transformers is in accordance with the EN 61558-2-15 reference standard “Particular requirements for insulating transformers for the supply of medical locations”.
This regulation prescribes additional requirements in order to safeguard the safety of the medical facilities. It is therefore not possible to use general purpose insulating transformers.

TI - Why does the technical specifications table show a ratio between inrush current and rated one of ca. 17 times when IEC 60364-7-710 reference standard prescribes a maximum of 12?

The rated current is not a RMS value, and therefore it is necessary to extract the peak value multiplying it by a factor square root of two. Dividing the inrush current by the rated current RMS, the result shall be a ratio equal to 12.


ISOLTESTER-DIG - Shall I avoid the protection related with the insulation monitoring device by means of a fuse, in order to avoid the risk of the monitor being disconnected?

The protection of the insulation monitoring device is necessary to protect the device from short circuits, in particular at the end of the equipment useful life. Without a suitable protection, a fire could be produced which should damage seriously the switchboard.For these reasons, in accordance with the IEC 60364 reference standard, the switchboard manufacturer cannot ignore the duty of protection.

It is also true that the insulation monitoring device cannot be accidentally disconnected for several reasons:

  • QSO Switchboards are equipped with a locked door. Only qualified and authorized personnel are expected to open it.
  • The E 91hN/32 fuse holder that protects the insulation monitoring device has no disconnecting performance under load, and therefore, in order to open the handle it is necessary to operate on the circuit upstream, disconnecting this way the operating theatre from the supply.
  • The E 91hN/32 fuse holder is sealed, and it may only be opened intentionally.

ISOLTESTER-DIG - What does HI_ which can be displayed on ISOLTESTER-DIG- RZ insulation monitoring device mean?

It means high insulation. ISOLTESTER-DIG-RZ displays, thanks to its three digit display, the real time insulation measure up to 999 kΩ. HI appears whenever the detected insulation is higher than this value.

ISOLTESTER-DIG - What does LF_ which can be displayed on ISOLTESTER-DIG-RZ insulation monitoring device mean?

It means “Link Fail”. ISOLTESTER-DIG-RZ display is capable of carrying out an internal self diagnosis to verify whether the measurement of the insulation is correctly performed. If the indication LF appears, it may mean that:

  • The device has not been wired correctly. In this case it is necessary to verify the wiring according to the installationelectrical scheme.
  • There are electrical devices that discharge some direct current interference on the PE safety conductor which affects ISOLTESTER-DIG-RZ measuring signal.

In this case it is necessary to verify the dispersion by means of a tester. ABB has specifically developed ISOLTESTER-DIG-PLUS in order to operate also in a strongly interfered

ISOLTESTER-DIG - Which insulation value shall I set on ISOLTESTER-DIG as insulation threshold?

There are not normative prescription. It all depends on the level of protection you want for the system. The higher the threshold, the higher the protection. On the other hand, the higher the threshold, the higher the possibility to be warned. A useful recomendation may be setting the threshold around 20% below the insulation measured in standard operating conditions.

ISOLTESTER-DIG - How do I enter ISOLTESTER-DIG setup menu?

Press “MINUS” and “SET/RESET” pushbutton simultaneously.

ISOLTESTER-DIG - How do I access the ISOLTESTER-DIG regulator menu?

Press “SET/RESET” pushbutton.

ISOLTESTER-DIG - How is it possible to connect 99 ISOLTESTER-DIG-PLUS to a single PLC with only few input channels?

The connection between ISOLTESTER-DIG-PLUS and the PLC is via bus. This mean that no point to point connection is needed and only one PLC input is used.

QSO - Does ABB release the QSO declaration of conformity?


QSO - Is it possible to use the same QSO switchboards to feed two (or more) group 2 medical facilities?

The IEC 60364-7-710 reference standard does not allow this application.
Any medical facility must be supplied by a dedicated medical insulating transformer. “For any group of functionally connected facilities at least an IT-M system is necessary” (article 710.512)

QSO - Has the QSO switchboard got an integrated change-over device?

The QSO switchboards does not perform switching functions to safety power supply. This functionality is required by the installation standard IEC 60364-7-710 (or by the relevant national rules) while the distribution boards must comply with the IEC 61439 series of standards.
As the presence of the changeover in the group 2 switchboards is not yet necessary, though it could be one of the possible measures that can  be used, the installer responsible for compliance with the IEC 60364-7-710 standard must do otherwise to guarantee this function.

QSD - How many signalling panels can I connect to each insulation monitor?

You can connect up to 4 remote parallel signalling panels, without adding any auxiliary supply.