Isolation Unit

Products

  • Air Cooled Series
  • Water Cooled Series

An Electrodynamic Vibration System is a combination of multiple systems – electrodynamic shaker, power amplifier, vibration controller, and accelerometer are the four main systems that come together to make an Electrodynamic Vibration System. A power amplifier consumes high power and a vibration controller consumes low power, therefore the power source for these two systems is different, which results in a ground loop. Input stage of the power amplifier is generally differential to avoid ground loop but a differential stage has its limitations in a high power system. Further, Earth connection to an electrodynamic shaker is generally dedicated to ensure human safety, while the Earth connection to vibration controller is from its low power source, which also results in a ground loop.

Vibration Testing has become very demanding and requires an Electrodynamic Vibration System to deliver high dynamic range. Ground loop results in line noise of single phase and three phase entering the vibration controller and adversely affecting any low acceleration level vibration tests. This noise reduces the systems dynamic range as low acceleration level vibration test cannot be performed which has a sever impact on the customer.

In parallel to this, many customers want to perform live testing of their payloads. At times payloads are given electrical power externally and at times payloads are acting like a generator creating electricity to achieve this. This electrical power, if kept in a closed loop without any leakage does not affect the system, but that cannot be ensured. Some payloads inherently have leakage current, and some payloads have failure modes during vibration testing which can result into leakage current. Without isolation, this leakage current can cause damage to the electronics inside an accelerometer, vibration controller, and power amplifier. Presence of electronics is increasing inside every system and so is the demand for live testing. An Electrodynamic Vibration System that cannot survive leakage current defeats the purpose of such a system.

To address the growing complaints of this nature, Sdyn has developed a 9 Channel Isolation Unit which can galvanically isolate analog signals between 1Hz to 5kHz and ±10Vpeak up to 1500Vrms with very high amplitude and phase accuracy. This unit is powered by single phase power and is of 1 unit height (1.75 inches) in a rack mountable encloser. The first 8 channels are for connection between accelerometer and vibration controller or any other data acquisition system. They offer direct coupling of IEPE / ICP / CCPD and Charge type Accelerometer with 3dB and 6dB gain options. The last channel is for connection between the Drive / Servo output of a Vibration Controller to a power amplifier of an Electrodynamic Vibration System.

This unit offers input to output and channel to channel isolation of 1500Vrms for all channels. Its internal design is very robust offering continuous short circuit protection, operation over a wide temperature range, optocoupler based isolation, plastic encapsulated BNC connectors, toggle switches for adjusting coupling type and gain for accelerometers, isolated ground connections for Drive / Servo signal, and a universal input power. It is compatible with every Electrodynamic Vibration System, Control System, and Data Acquisition System in the world. Multiple units can be mounted in a single racks to achieve any number of channels for isolating accelerometers.

Each unit is supplied with 1 no. of power cable, 8 nos. of 10-32 to BNC low noise cables, 10 nos. of BNC to BNC low noise cables, and 2 nos. of grounding cables. Length of all these cables are as per customer requirement. Installation, operation, calibration, and troubleshooting manuals along with warranty and calibration certificates are also provided.

The process of re-calibration has been made simple by adding an internal signal generator which generates a sine wave for calibration purpose. Calibration requires a small screwdriver, BNC to BNC low noise cable, and a BNC to Banana Cable which are provided along with the system. A multi-meter is also needed which the customer must arrange at their site. Sdyn recommends using a 5 and ½ digit or better multi-meter of a reputed make for the purpose of calibration. Top cover of this unit needs to be removed for calibration to allow access to the potentiometers that are adjusted during calibration. The entire process is clearly defined in the calibration manual and user can generate a calibration certificate themselves also. Via

Electrical Specifications

Input Specification (Channel 1 to 8)

Frequency Range ………………………………………………………………………………..

1 Hz to 5 kHz
Voltage Range
±10 VPEAK
Coupling Type
AC Single Ended Voltage, IEPE, and Charge
Coupling Selection
Manually via Toggle Switch
IEPE Voltage
+24 VDC
IEPE Current
4 mADC
Interface Connector
BNC
Output Specification (Channel 1 to 8)

Frequency Range ……………………………………………………..
1 Hz to 5 kHz
Voltage Range
±10 VPEAK
Current Capability
20 mA
Gain Options
0dB (1:1), 3dB (1:1.5), and 6dB (1:2)
Gain Selection
Manually via Toggle Switch
Interface Connector
BNC
Input Specification (Channel 9)

Frequency Range ………………………………………………………………..
1 Hz to 5 kHz
Voltage Range
±10 VPEAK
Coupling Type
AC Single Ended Voltage
Input Impedance
25 kΩ
Interface Connector
BNC
External Ground Impedance
10 Ω
External Ground Connector
4 mm Plastic Encapsulated Banana
Output Specification (Channel 9)

Frequency Range ………………………………………………………………..
1 Hz to 5 kHz
Voltage Range
±10 VPEAK
Current Capability
20 mA
Interface Connector
BNC
External Ground Impedance
10 Ω
External Ground Connector
4 mm Plastic Encapsulated Banana
Channel Specification
Input to Output Amplitude Accuracy

0.1% ……………………………………………………
Input to Output Phase Accuracy
0.1°
Dynamic Range
> 120 dB
Channel to Channel Cross Talk
< -100 dB
Input to Output Isolation Voltage
1500 VRMS
Channel to Channel Isolation Voltage
1500 VRMS
Calibration Signal Specification
Voltage

 1 VRMS …………………………………………/
Frequency
1 kHz
Interface Connector
BNC
Input Power

Voltage ………………………… ………………………… …………………………

90 VAC to 260 VAC ………………………………..

Frequency …………………………………………………
47 Hz to 63 Hz

Power………………………………………………………………………………….
20 W

Mechanical Specifications

Dimensions…………………………………………………………………………………….

482 mm (L) by 280 mm (W) by 44 mm (H)……….

Weight……………………………………………………………………………………………………………….
2.5 kg
Material
Aluminium
Colour
Black
Mounting
19” Rack Compatible

Environmental Specifications

Operating Temperature…………….
5°C to 75°C
Storage Temperature
0°C to 75°C
Humidity
< 90% (non-condensing)
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