The SA series power amplifier adopts conventional Pulse Width Modulated (PWM) technology. In PWM circuit, the input signal is modulated in a very high frequency ON/OFF logic drive pulses. These ON/OFF logic drive pulses control the IGBTs switching ON and OFF. During the switching ON, the output stages deliver large current with only a very small voltage drop across the IGBTs. During the switching OFF, there is no current flow. Thus, in either stage, there is very little power loss in IGBT. Because of the low power losses, PWM amplifier can be air cooled and located where ambient temperature lower than 40 Celsius degree.
By modulating the input signal into high frequency and demodulating it through L-C filter, a very pure and big power output signal is produced.
Power Supply (PS) and Rectifier Module (RM)
All power comes from a set of three-phase power supplies. The three-phase power supply is first passed through the circuit breaker and then divided into groups by fuses.
A three-phase power transformer after the fuse, the conventional isolation transformer provides two separate 3-phase power outputs for the rectifier module (RM). The RM contains 2 full-wave rectifiers (one for power modules and one for the field), heat sinks, capacitors, connectors and cooling fans. The RM provides 210VDC (V + to V-) for the power module and 270VDC (G1, G2) for the field coil, all of which float to the ground. In a vibrating system, the field power is separated from the amplifier.
If the blower is powered by a power amplifier, there is a connection interface for the three-phase power to enter the blower motor. If the blower is powered by an additional motor starter box (MS), an additional three-phase power supply is required.
If the vibrator is equipped with a sliding table, the three-phase power supply will be divided into a separate group to enter the pump motor.
Master Logic Module (MLM)
The MLM includes：1. All low level stages of the PWM circuit and peak current limiting circuit.2. A DC to AC inverter circuit for powering the IGBT drive circuit in the power module.3. All logic circuits for monitoring all of the system interlocks and protections.4. All status lights.5. Digital meter to display field voltage & current and main voltage.6. Control circuits to start and stop the amplifier, field supply and shaker blower.7. Digital interface to control panel.All interlocks are brought to ‘JUNCTION PCB’ on the rear power plate.2The master logic module can drive up to ten power modules or slave logic modules which is required if the total power module number is above 12.
Power Module (PM)
PM is a high-frequency pulse-width modulated power inverter with a rating of 15 kVA.
It includes:
1. A full H bridge driver board with optically isolated input.
2. Output H bridge mounted on air cooled heat sink.
3. Two stages output L-C filter.
4. Cooling fan and its 12VDC power supply
5. Output current monitor circuit to protect PM avoiding over current.
PM is supplied by an unregulated DC supply (210VDC) through power connector of
V+ & V- which are fused inside of PM
Control panel
CP is mounted on the front door of amplifier. It consists of:
1. ‘ON’, ‘OFF’, ’Emergency Stop’ and ‘Gain POT’ switches.
2. Digital meters to display output voltage and output current.
3. Interlock and protection lights