Certainly! To create a test case generator for the given problem, we need to generate:

1. The number of devices \(N\).
2. The list \(A\) of size \(N\), where each element \(A[i]\) represents the power consumption or supply of the \(i\)-th device.
3. A list of \(N-1\) unique cables connecting the devices, represented as pairs \((U_i, V_i)\).

Here's a Python function that generates random test cases for the problem:

```python
import random

def generate_test_case():
    N = random.randint(1, 5000)  # Number of devices
    A = [random.choice([-1, 1]) * random.randint(1, 10**9) for _ in range(N)]  # Power supply/consumption for each device

    # Generate a random tree structure
    edges = []
    if N > 1:
        nodes = list(range(1, N + 1))
        random.shuffle(nodes)
        for i in range(1, N):
            U = nodes[i]
            V = nodes[random.randint(0, i - 1)]
            edges.append((U, V))

    # Formatting the output
    test_case = f"{N}\n"
    test_case += ' '.join(map(str, A)) + '\n'
    for (U, V) in edges:
        test_case += f"{U} {V}\n"

    return test_case

# Example usage
print(generate_test_case())
```

This function does the following:
1. It generates a random number \(N\) within the given constraints.
2. It generates a list \(A\) of size \(N\) where each element is a random non-zero integer between \(-10^9\) and \(10^9\).
3. It generates \(N-1\) edges ensuring they form a valid tree structure by connecting nodes in a way that each node is connected to some previous node, ensuring all nodes are connected.

You can call `generate_test_case()` to get a new test case each time. This function ensures the constraints of the problem are met and generates valid random test cases for the problem.