GE industrial control system power boards DS200DCFBG1A and DS200DCFBG1B

SAFETY SYMBOL LEGEND

Indicates a procedure, practice,

condition, or statement that, if

not strictly observed, could result in personal injury or death.

Indicates a procedure, practice,

condition, or statement that, if

not strictly observed, could result in damage to or destruction

of equipment

NOTE Indicates an essential or important procedure,

practice, condition, or statement.

FUNCTIONAL DESCRIPTION

This equipment contains a potential hazard of

electric shock or burn. Only adequately

trained persons who are thoroughly familiar

with the equipment and the instructions

should install or maintain this equipment.

INTRODUCTION

NOTE

The DCFB board is used in DC2000, CB2000,

EX2000, FC2000, GF2000, ME2000, and

AC2000 IGBT drive applications. The

EX2000 uses the board for a different purpose

than a drive does. When the information is

different for the EX2000 applications, it is

shown by italics in parentheses (NA = Not

Applicable).

The DS200DCFB Power Supply Board (DCFB) receives

38 and 115 V ac (24 V dc) input power from the control

power transformer (CPT), and provides control-level

power to the drive and 115 V ac power (NA) to the enclosure fans. The DCFB board includes the following circuits:

• Control-level power supplies (+5, ±15, and ±24 V dc)• Motor field power circuits (except the SCR module)

• Driver circuits for the motor field SCR gate pulse

generators

• Circuits to monitor numerous ac line and dc motor

signals, including:

− Armature current(s) and voltage(s) (NA)

− Motor field currents (NA)

− Ac line current

− Ac line voltage magnitude and phase sequence

POWER SUPPLIES

The DCFB board receives 38 V ac (±10%) from the CPT (24 V dc). This voltage is full-wave rectified and filtered to produce the unregulated ±24 V dc outputs. The +24 V dc output is rated at 3 A and the –24 V dc output is rated at 1 A. Regulators on the DCFB board derive ±15 V dc from the ±24 V dc supplies. The ±15 V dc outputs are each rated at 0.8 A, of which 0.25 A is available for external loading. The DCFB board also generates a +5 V dc, 4 A output from the +24 V dc supply. The /PSEN signal on 2PL goes to a TTL low state when the +5 V dc supply is in regulation and the signal goes high if the +5 V dc supply goes out of regulation. When high, /PSEN generates a microprocessor reset on the Drive Control Card (SDCC/LDCC). The DCFB board provides isolated +5 and ±15 V dc supplies to power the armature current feedback circuits. The power supply outputs are protected against short circuits by fuses FU2 and FU3 (7 A, 2AG). Light-emitting diodes (LEDs) CR51 and CR55 provide blown fuse indication for these fuses. The 115 V ac output is protected by fuse FU1 (1/2 A, 2AG). Neon light LT1 provides blown fuse indication for FU1.

VOLTAGE AND CURRENT FEEDBACK VCO CIRCUITS

The DCFB board includes voltage-controlled oscillator (VCO) circuits that convert input voltages to frequency signals. Each VCO has a nominal output frequency of 250 kHz. The output frequency varies from 0 to 500 kHz, depending upon the input voltage. VCO outputs are sent to the SDCC/LDCC board through connector 1PL to provide feedback of the following: 

• SCR bridge ac input voltage 

• Output bridge voltage

• Motor voltage (NA) 

• Millivolt signals from field shunts 

• Millivolt signals from armature shunts The output bridge VCO circuit provides feedback to the SDCC/LDCC board through connector 1PL, pin 13 (1PL13). DIP switch SW4 is used to scale the voltage applied to the circuit. A frequency-to-voltage reconstruction circuit provides a diagnostic signal for testpoint TP37 on the SDCC/LDCC board through 1PL-37. The diagnostic bridge voltage signal can be viewed using an ac-coupled oscilloscope. The second VCO provides feedback of the motor voltage to the SDCC/LDCC board through 1PL-39. DIP switch SW5 is used to scale the voltage applied to the circuit. Two other VCO circuits provide feedback of the input voltage from a shunt. The VCO output frequency signals are sent to the SDCC/LDCC board through connector 1PL. The DCFB board also includes two motor armature VCO circuits. The frequency output signals from these VCOs are sent to the SDCC/LDCC board through 1PL-8 and 1PL-10. These VCOs are at the potential of the armature bus and are fed by an isolator.

MOTOR VOLTAGE ATTENUATION CIRCUIT

The DCFB board includes a motor voltage attenuation circuit that provides an analog representation of the motor voltage. This signal is sent to the SDCC/LDCC board through 1PL-6. The attenuation circuit is biased at 2.5 V, and can vary from 0 to 5 V depending on the motor voltage. DIP switch SW6 is used to scale the motor voltage feedback.

AC LINE MAGNITUDE AND ZERO CROSSING

The DCFB board contains amplifier circuits that process the ac line-to-line voltages. The voltage feedback signals are sent to the SDCC/LDCC board through 1PL-11, 1PL12, and 1PL-29. These signals are used to detect power bridge SCR failures and may also be used to derive the synchronization signal for the firing of the SCRs. DIP switches SW1, SW2, and SW3 are used to scale the ac line voltage feedbacks.

AC LINE CURRENT TRANSFORMER INTERFACE

In some applications, the drive’s ac input lines L1 and L3 include ac line current transformers (ACCTs). Switch SW7 on the DCFB board is used to select the burden resistance as a function of rated 1 per unit (pu) dc output current. (The rated 1 pu dc output current is defined as 0.5 V across the DCFB board’s ACCT burden resistors.) The DCFB board sends the ACCT signals to the SDCC/LDCC board through 1PL. The SDCC/LDCC board uses the ACCT signals to check for commutation failure and ac instantaneous overcurrent (IOC). Testpoint ACCT on the DCFB board may be used to view the ACCT signals.