7SG15 MicroTAPP Description of Operation
©2013 Siemens Protection Devices Limited
Chapter 1 Page 34 of 38
10 Relay Hardware
MicroTAPP relays are housed in either the Epsilon E8 or E12 case, depending on input/output configurations. The
fascia PCB forms the human machine interface (HMI), with pushbuttons for entering settings, an LCD for
displaying alphanumeric messages and LEDs for indication.
Peripheral devices such as output relays, status inputs and the communications interface are accommodated on
the remaining PCBs.
Two options of Inputs and Outputs are available: -
Inputs
Outputs
E8 case (MT101)
11 5
E12 case (MT102 or MT101 with extra I/O)
19 13
Appendix B at the end of this section shows a rear view of the relay with the connections shown for both the
arrangements.
10.1 Internal Construction
The design for the internal arrangement of each case has been chosen to provide a high level of EMI screening,
using multi-layer PCBs with ground planes, RFI suppression components and earthed metal screens.
The case is divided internally into noisy and quiet areas in order to improve noise immunity and reduce RFI
emissions. The only direct connection from the quiet components to the external environment is via the optical
serial communications interface, which is immune to radiated or conducted interference.
10.2 Front Cover
After the relay has been commissioned it is sealed by fixing a clear plastic cover over the front. This allows the
user to see the entire front of the relay and enables normal operations of the control of the tap changer while
preventing changes to operational settings. If required a security seal can be applied to the cover fixings.
10.3 Terminal Blocks
These are of the standard Epsilon design. All inputs and outputs (except for the serial communications interface)
are made through these connectors. The terminal arrangement is shown in the appendix B at the end of this
section
