In the case of Pickering's BRIC matrices, for example, one model contains 2238 relays. Of these, 2208 are matrix bodies, 24 are isolation relays, and 6 are standby relays (accessories are not involved in the operation and can be excluded from the MTBF calculation). According to the working principle of the product, the isolation relays automatically follow the matrix relay, and in most applications their switching frequency is equal to or slightly lower than that of the matrix relay, so there is no need for a separate calculation.