MSCDN – MP2A Description of Operation
1 Introduction
MSCDN-MP2A
Thermal Overload and Open Circuit
Protection
C1
C2
R2
R1
R1
49
R2
49
50
AN1C1 - C3
AN2C1 - C3
Figure 1 – MSCDN-MP2A Overview
The MSCDN-MP2A relay provides wide bandwidth, true RMS phase by phase thermal Overcurrent protection and open
circuit protection for the damping resistors in a mechanically switched capacitor bank. Together with its sister units
MSCDN-MP1 and MP2B, this protection unit offers a complete solution for Main 1 and Main 2 protection of EHV
capacitor banks.
2 Hardware Description
2.1 General
The structure of the relay is based upon the Modular II hardware and software platform illustrated in Figure
2 where the required cards plug in from the front after opening the front fascia. Modules are interconnected
by means of ribbon cable. The relay can be supplied in standard Epsilon case size E12 or E16. The
Modular II design provides commonality between products and spare parts across a range of protection
and control relays including Duobias, Ohmega, Delta, Tau and Iota.
Typical Configuration :
Analogue Inputs
Status Inputs
Output Relays
Case
8 11
13
E12
Each analogue module requires three inputs; for measuring the CT secondary line currents from each of
the three phases A, B and C.
The unit consists of the following modules:
©2010 Siemens Protection Devices Limited
Chapter 1 Page 3 of 13
