Examples provided here are purely for illustrating software features and functionality.

BlockSim Example 5 – Remote Telecommunications System

Download Example File for Version 10 (*.rsgz10) or Version 9 (*.rsr9)

A telecommunications system is to be constructed in an uninhabited stretch of jungle. The system consists of a transmitter and receiver with six relay stations to connect them.

The relays are situated so that the signal originating from one station can be picked up by the next two stations down the line. For example, a signal from the transmitter can be received by Relay 1 and Relay 2, a signal from Relay 1 can be received by Relay 2 and Relay 3 and so forth. Thus, this arrangement would require two consecutive relays to fail for the system to fail. (This is also known as a consecutive-k-out-of-n:F system.)

Furthermore, the transmitter and receiver are made up of three subassemblies each, while the relay stations have two subassemblies each (all in series). Specifically:

• Subassembly SPS1 (solar power supply) is common to all three.
• The transmitter has subassemblies TRC1 and TRC2, in addition to SPS1.
• The receiver has subassemblies RCR1 and RCR2, in addition to SPS1.
• The relay stations have a subassembly RLYC1 in addition to SPS1.

The following picture shows the RBD of the telecommunications system in BlockSim.

Figure 1: RBD of Telecommunications System

Each component (transmitter, receiver, relay) is represented by a subdiagram block. The following pictures show the subassemblies of each component.

Figure 2: RBD of Transmitter

Figure 3: RBD of Receiver

Basic Reliability Analysis

The failure distributions for each subassembly are given in the following table.

Component	Failure Distribution	Parameters
SPS1	Weibull	Beta = 2 Eta = 25,000 hours
TRC1	Weibull	Beta = 3 Eta = 20,000 hours
TRC2	Exponential	Mean = 85,000 hours
RCR1	Exponential	Mean 150,000 hours
RCR2	Weibull	Beta = 2 Eta = 30,000 hours
RLYC1	Exponential	Mean = 100,000 hours

The objectives of the analysis are to obtain the reliability of the system after 1,000 hours and to determine whether the failure of the redundant relays (1 through 6) have the same effect on the system reliability. In other words, does it matter from a reliability perspective which specific relay fails?

Step1: Use the information given in Table 1 to configure the universal reliability definitions (URDs) of each block in Figures 2 to 4. For example, the following picture shows the Block Properties window of SPS1. The inset shows the Model Wizard, which allows you to define the failure distribution of the block. The URDs of the other blocks can be configured in a similar manner.

Figure 5: Block Properties Window of SPS1 and the Model Wizard (inset)

Figure 6: Analytical QCP

Figure 6: Standardized Residuals plot.

Based on this analysis, the projected shelf life of this product is 15.6 months. The desired result can also be obtained from the QCP, as shown next.

In this analysis, the relays are reliability-wise identical; however, their position within the diagram matters. This is best illustrated by the reliability importance plot shown next. As you can see, a specific relay failure affects the system differently due to its position within the system. Specifically and in order of importance, the greatest impact is if relay 2 or 5 fails, followed by relay 4 or 3 and then by relay 1 or 6.

Figure 7: Reliability Importance Plot