Basler CBS 310/320 Current Boosting System

Column 3: Turn ratio corresponding to different excitation currents (1.8/3.6/7.2 Adc)

Selection method: Find the row where the short-circuit current is located in column 1 → Find the value closest to the required excitation current in column 3 → The turn ratio corresponding to the intersection point is the result (for example, 4:209 represents 4 turns primary/209 turns secondary).

4. Precise selection method (refinement of Table 2-1)

When the standard selection results in too many primary turns (insufficient window space), precise calculation methods can be used to reduce the number of turns:

Calculate the required CT secondary current: ICT_SEC=IField × 1.25 (redundancy factor)

Calculate primary ampere turns: PAT=209 × ICT_SEC

Calculate the number of primary turns: NPRI=PAT/(1.73 × ILINE_3ph), rounded up to the nearest integer

Verify whether the continuous ampere turns exceed the CT rated capacity

Selection case analysis

Generator: 125kVA/480Vac/150A full load/15 Ω excitation winding

CBS 310 short-circuit excitation current: 90V/15 Ω=6.0A

Check the curve for a short-circuit current of 525A (too high) and determine the target as 450A

Required excitation current 5.14A, series current limiting resistor: RS=90/5.14-15=2.5 Ω

According to the table, the turns ratio is 4:209, with 4 turns x 1 wire x 2 phases=8 conductors passing through the CT window, and the window size meets the requirements

Installation and Wiring Engineering Guide

1. Mechanical installation

The boost module can be installed in any direction and uses 1/4 "fasteners. The appearance is shown in Figure 2-1.

CT requires 5/16 "bolts to be firmly fixed at 6 installation points, and the structure must withstand transportation and operational vibrations.

2. Electrical wiring

The manual provides 5 typical wiring diagrams (Figures 2-5 to 2-9), covering:

Standard wiring for CBS and 208-240Vac generators

CBS and 416-480Vac generator wiring

Wiring scheme with isolation transformer

Wiring in conjunction with MVC manual voltage controller

Dual CT configuration (one CT per phase)

Key wiring principles:

The generator wires must have insulation levels that match the operating voltage, and insulated cables or busbars can be used.

The electric force under short-circuit conditions is extremely high, and the busbar/cable must be reliably fixed to prevent displacement or short circuit.

Connect a DC voltmeter between the P and N terminals of the CBS module (to be used for verifying boost status).

3. Auxiliary terminal description

CB+/CB -: Accept trigger signal from APR regulator (10mA @ 1.5V)

P/N: Boost DC output to excitation winding

CT input: AC current signal from CT (see CT wiring diagram for terminal identification)

Debugging and functional verification

1. Installation verification (no-load+load test)

No load start, measure the P-N terminal voltage, which should be about -1.5 Vdc (negative value indicates standby state).

Apply a load to drop the voltage by ≥ 25%, observe:

BOOST indicator light is on

P-N voltage jumps to ≥ 90Vdc (CBS 310) or ≥ 180Vdc (CBS 320)

Record the voltage recovery time to ensure it is less than 2 cycles.

2. Verification of turns ratio

Measure the generator line current under balanced load

ILI L and CT secondary current ISEC, verify that the actual ratio matches the calculation:

ISEC=1.73×NP×IL/NSEC

If the deviation is greater than 10%, the number of turns needs to be recalculated or the CT wiring needs to be checked.

3. Bench testing (offline verification)

Manual Figure 3-1 provides a simple bench test circuit (including a 120Vac power supply, indicator lights, and switches) for verifying the basic functionality of the CBS module without connecting to a generator

SWI closed → all input lights are on, BOOST light is off (standby)

SWI disconnected → input light turns dark, BOOST light and output light turn on simultaneously (boost simulation)

This test can quickly screen out faulty modules before loading.

Typical troubleshooting guide

Although the CBS system is highly reliable, the following faults occasionally occur and need to be investigated:

Phenomenon 1: BOOST light does not light up when fully loaded/short circuited

Check if the CB+/CB - terminals of the APR regulator output a trigger signal (normally around 1.5V/10mA)

Check if APR has entered the forced excitation mode (if the voltage is below 85% of the set value)

Check if the CT input circuit is open circuit

Phenomenon 2: Insufficient boost output (P-N voltage below rated value)

Check if the CT turns ratio is too small (insufficient primary turns)

Check if the resistance of the excitation winding exceeds the adaptation range (CBS 310 needs to be ≥ 12.5 Ω)

Check if the CT secondary side wiring terminal is correct (confirm the corresponding terminal for 209 turns)

Phenomenon 3: BOOST light mistakenly lights up when unloaded

Check if there is a short circuit or leakage current in the CB+/CB circuit

Check if the APR regulator offset is normal

Phenomenon 4: CT overheating or abnormal noise

Check if it exceeds the maximum continuous current capacity of CT (BE 21331-001 is 800A)

Check if additional eddy currents are generated when the primary conductor passes through the CT window (a single core should be used to avoid multiple turns and forming a closed loop)