BRUEL & KJAER 2719 - User Manual

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Summary

Controls

Front Panel

Describes controls, display, and status LEDs on the front panel, including V/C Mode and Current Limit.

Back Panel

Explains rear panel connectors for signal input/output, monitoring, and mains voltage selection.

Operation

System Checks and Connections

Details essential system checks and connections to ensure correct and safe operation before connecting mains supply.

Operating Procedure

Step-by-step guide to operating the amplifier, including setting controls, connecting signal generators, and managing output levels.

Warning Lamps and Fault Detection

Explains the function of warning lamps and provides probable causes for amplifier shut-down or faults.

Service and Repair

Safety Warning for Servicing

A critical warning about disconnecting power before panel removal and only allowing skilled persons to perform internal adjustments.

The Brüel & Kjær Power Amplifier Type 2719 is designed to drive small vibration exciters, specifically the 112 N (25 lbf) Vibration Exciter Type 4808 and the 45 N (10 lbf) Vibration Exciter Type 4809. It features an adjustable RMS output-current limit, allowing it to safely drive the 4809 to full rating.

Function Description:

The Type 2719 is a versatile power amplifier with a usable frequency range from DC to 100 kHz. It delivers a rated AC output of 180 VA into a 0.8 Ω exciter or resistive load, within the frequency range of DC to 15 kHz (±0.5 dB). The maximum voltage gain is 40 dB. The amplifier employs heavy negative feedback to minimize harmonic content in the output and maintains excellent stability despite temperature and supply line variations. It can operate as either a voltage generator with low output impedance and a flat voltage frequency response, or as a current generator with high output impedance and a flat current frequency response.

Important Technical Specifications:

Power Output Capacity: 180 VA into a 0.8 Ω exciter or resistive load at 25°C and nominal mains voltage. Reduced to 144 VA into a 1 Ω exciter or resistive load at 40°C or 10% above nominal mains voltage. Output is via a 4-pin Neutrik® Speakon® socket at the rear panel.
Output Voltage Capacity: 12 V RMS, DC to 15 kHz, via 4-pin Neutrik® Speakon® plug.
Output Current Capacity: 7.5 A RMS at or below 5 Hz, 15 A RMS from 40 Hz to 10 kHz, and 12 A RMS at 15 kHz.
Frequency Range: Full capacity from 40 Hz to 10 kHz. Reduced capacity from DC to 100 kHz.
Frequency Response (Typical small signal in low impedance mode):
- DC Input: DC to 15 kHz ±0.5 dB; DC to 100 kHz ±3 dB.
- AC Input: 15 Hz to 15 kHz ±0.5 dB.
- Inputs are provided via two separate BNC sockets at the rear panel.
Input Impedance: >10 kΩ.
DC Stability: Less than 50 mV drift from 0 V for ±10% variation of mains supply from nominal, and for 10°C to 40°C (50°F to 104°F) variation in ambient temperature.
Power Requirements: Single phase 100, 120, 230 V RMS, ±10%. Approximately 400 VA at full load. Power insert connector with fuse holder and voltage selector at the rear panel.
Dimensions: Height: 2HE equivalent of 88 mm. Width: 482.6 mm (19 in) with flanges for standard 19-inch rack mounting. Depth: 350 mm (13.8 in).
Weight: 14.0 kg (31 lb.).
Environmental Conditions:
- Operating Temperature: +5 to +40°C (41 to 104°F).
- Storage Temperature: -25 to +70°C (-13 to 158°F).
- Humidity: 90% RH (non-condensing at 40°C (104°F)).
Compliance with Standards: CE (EMC Directive), EMC Requirements of Australia and New Zealand, EN/IEC 61010-1, UL 61010-1, EN/IEC 61000-6-2, EN/IEC 61000-6-4, CISPR22 Class A limit, FCC Rules Part 15, EN/IEC 61326.
Protection: Input signal is removed and an indicator lamp is lit when preset limits are exceeded for Driver Coil Current (true RMS adjustable limit 1 to 15 A RMS), Power Transistor Temperature, Heat Sink Temperature. Output Signal Distortion does not cause shut down. Electronic peak current limiting is also included.

Usage Features:

Front Panel Controls:
- Current Limit A (RMS): A single-turn potentiometer for limiting RMS current output.
- Display: LCD shows output AC current and voltage.
- LED Indicators:
  - Temperature (red): Indicates overheating of Power MOS Output Transistors, leading to amplifier shut-down.
  - Current (red): Lights when output current exceeds the set Current Limit, leading to amplifier shut-down.
  - State (green): Indicates amplifier power is On.
  - Voltage or Current Mode (green): Shows the selected output mode.
  - Interlock (red): Lights when the interlock circuit is activated.
  - 0° or 180° (green): Indicates phase shift from input to output.
  - Distortion (yellow): Lights when output voltage or current clipping occurs.
- V/C Mode: Selects feedback and output impedance modes.
  - Voltage Mode: Provides constant voltage characteristics, low output impedance, and flat voltage frequency response, ideal for best acceleration waveform in most vibration tests and multiple-exciter applications at low frequencies.
  - Current Mode: Provides constant current characteristics, high output impedance, and flat current frequency response, useful for constant force generation in single-exciter fatigue tests and multiple-exciter resonant mode studies.
- Phase: Sets output/input phase shift to 0 or 180 degrees.
- Power: Mains On/Off button.
- Variable Gain (dB): Single-turn, logarithmic potentiometer for continuous adjustment of input signal level. Turning fully anticlockwise prevents power surges and activates Reset.
Back Panel Connections:
- Signal Input AC: BNC socket for capacitive-coupled input (e.g., from a vibration exciter controller or generator). -0.5 dB lower limiting frequency is 15 Hz. Full output with 2.4 V RMS input.
- Signal Input DC: BNC socket for direct-coupled input. Allows DC offset voltage for centring exciter's vibration table. Input impedance >10 kΩ. Full output with 2.4 V RMS input.
- Voltage Monitor: BNC socket for displaying amplifier voltage waveform (including DC component) on an oscilloscope. Monitor signal is amplifier output voltage attenuated 20 dB (0.1 V/V).
- Current Monitor: BNC socket for displaying amplifier output current waveform (including DC component) on an oscilloscope. Monitor signal is amplifier output current in 0.1 V/A.
- Output: 4-pin Neutrik® Speakon® socket for connecting an exciter.
- Mains Voltage Selector and Fuse: For selecting 100, 120, or 230 V ±10% (50 to 60 Hz) single-phase AC mains supply and for fuse replacement.
- Mains Input: Socket for power cable connection.

Maintenance Features:

Fuse Check and Replacement: The mains fuse and fuse holder are integrated into the voltage selector on the back panel. Fuses are T6.3 A slow blow for 100 V and 120 V operation, and T3.15 A slow blow for 230 V operation. Only specified fuses should be used.
Rack Mounting: Designed to fit into a 19" standard rack system. Rubber feet must be removed for rack mounting.
Cooling: Requires free flow of cooling air through the input vent (top cover) to the output vent (back panel) to prevent overheating. Overheating will cause automatic shut-down.
Safety: The signal ground line is permanently connected to the chassis at one point to minimize mains-carried noise. Proper grounding considerations are detailed for complex measurement setups to avoid mains hum.
Service and Repair: The device is designed for reliable operation. In case of impaired function or safety, it should be disconnected from mains and secured. Repairs should only be performed by qualified service personnel. Disconnect all power before removing protective panels.