What is the maximum permissible continuous load on each TRU?

What is the maximum permissible continuous load on each TRU?

• A. 120 Amps
• B. 100 Amps
• C. 150 Amps
• D. 90 Amps

Answer: (A)

TRUs have a defined continuous current rating that keeps them from overheating while supplying the DC buses. For the CRJ-550, each Transformer Rectifier Unit is allowed to deliver up to 120 amps continuously. This rating lets the two TRUs share the load safely—giving up to 240 amps total when both are used—while leaving headroom for normal operation and cooling. If a single TRU is pushed beyond its 120-amp limit, protective circuitry will limit or trip to prevent damage. So, the maximum permissible continuous load per TRU is 120 amps. Values below that would not reflect the intended maximum capability, while a higher value would exceed the TRU’s thermal and protection limits.

TRUs have a defined continuous current rating that keeps them from overheating while supplying the DC buses. For the CRJ-550, each Transformer Rectifier Unit is allowed to deliver up to 120 amps continuously. This rating lets the two TRUs share the load safely—giving up to 240 amps total when both are used—while leaving headroom for normal operation and cooling. If a single TRU is pushed beyond its 120-amp limit, protective circuitry will limit or trip to prevent damage.

So, the maximum permissible continuous load per TRU is 120 amps. Values below that would not reflect the intended maximum capability, while a higher value would exceed the TRU’s thermal and protection limits.