Min Specs.docx

CUI

Requirements Item Definition The sensor consists of a sensing element, integrated preamplifier, a pressure tolerant housing, shielded twisted pair cable, and connector.

Functional Definition This is a low noise accelerometer that shall be capable of sensing vibrations and producing analog electrical signals proportional to the physical motion of the sensor in the direction of the sensing axis in accordance with the performance, electrical, physical and environmental requirements of this section.

The sensor shall provide these functions:

· Calibrated single axis accelerometer (Z-axis);

· Accelerometer preamplifier shall have input protection such that there is no degradation if it receives either CCLD power or 24V on the shield line;

· Accelerometer preamplifier shall have a single pole 15k Hz low-pass filter on the output signal to limit out of band signal;

· Accelerometer output signal shall be a current modulated signal

· Accelerometer preamplifier will be powered from Constant Voltage Line Drive (CVLD) circuit. NSWCCD will provide CVLD drive circuit example and electrical schematic.

· Accelerometer preamplifier shall be electrically isolated from the case Physical Interface The accelerometer shall have a captive 10-32 UNF mounting screw through its center located perpendicular to the case. The accelerometer shall have threads in the top third of the mounting bolt hole to keep the mounting bolt captive. The accelerometer shall have the capability to rotate 360 degrees about the captive screw. The mounting bolt shall not extend more than 0.375” beyond the base.

Electrical Interface The sensor electrical interface shall be CVLD. This is a type of two wire interface where a constant DC bias is provided to the sensor by a CVLD receiver and the sensor modulates AC current on the interface to pass analog signaling. The CVLD receiver uses a current sense device to recover the modulated current. A single twisted shielded pair (TSP) cable shall be used for this interface. The shield shall not be connected to the case of the accelerometer, but will be connected to the LEMO FGG.0K connector. The shield shall be a braid or a serve shield. See below for LEMO connector pin assignments:

· Pin 3 - Signal (White)

· Pin 2 - Shield

· Pin 1 - Return (Black) Performance Specifications All Performance requirements are referenced to 100 Hz and 20 degrees Celsius (68 F) unless otherwise noted Axial Sensitivity The axial sensitivity of the mounted accelerometer shall be 1000 microamps/g (+/- 5%) as measured at 100 Hz.

Dynamic Range The mounted accelerometer shall have a dynamic range >132 dB at 100 Hz.

Frequency Range The mounted accelerometer shall have frequency response flat within limits shown in Figure 1.

Figure 1 Frequency Response Linear Range The accelerometer shall have a linear range of at least 2 g peak. The amplitude linearity error shall be less than 1%.

Mounted Resonance Accelerometer shall have a mounted resonance greater than 25KHz.

Electrical Characteristics Settling Time Accelerometer shall have a settling time of less than 30 seconds to power up and to recover from an overload.

Output Noise Accelerometer output noise measure at one Hz resolution shall not exceed values listed in the below Table 1 and Figure 2.

Noise Floor Requirement

Table: 1

Figure 2 Noise Floor Requirement

Phase Response The phase response of the mounted accelerometer shall be measured during first article testing. All subsequent mounted accelerometers shall be within +/- 1 degree from 3 Hz to 10 kHz, when compared to the measured phase response from first article testing.

Power Requirements Accelerometer shall be capable of operating from a bias voltage of +15 VDC (±1VDC) and a bias current of 10 milliamps (±10%).

Output Impedance Accelerometer shall have an output impedance >100 KΩ Electrical Isolation The mounted accelerometer signal ground shall be isolated from the outer case by at least 50 Megohms at 50 VDC.

Pyroelectric Sensitivity The mounted accelerometer output due to pyroelectric effects shall be less than 0.005 g per degree Celsius.

Physical Characteristics The mounted accelerometer casing shall be hermetically sealed stainless steel and house the sensing elements and signal conditioning electronics.

Cable Cable shall be chainflex CF211.PUR hardwired to the accelerometer with a mechanical attachment and overmold for strain relief. The length of the cable shall be 15 feet unless otherwise specified in the purchase order.

Cable Attachment The cable attachment to the accelerometer shall be capable of withstanding a tensile load of 100 lbs. Any strength members inside the cable shall be tied at both ends.

Weight The weight of the mounted accelerometer shall not exceed 0.300 pound excluding the cable and cable strain relief.

Dimensions The mounted accelerometer diameter shall not exceed 1.25 inch not including the cable exit potting. The height shall not exceed 1.25 inch not including mounting screw.

Mounting Surface The accelerometer mating surface shall be flat within 0.0003 inches and shall have a minimum surface finish of 65 micro inches RMS.

Transverse Sensitivity The mounted accelerometer transverse sensitivity shall be less than 4% measured at 7 Hz.

Base Strain Sensitivity The accelerometer output due to base strains shall not exceed .005 g per microstrain at 250 microstrain.

Labeling Each accelerometer shall be clearly and permanently labeled with a part number and serial number.

Environmental Requirements Temperature The mounted accelerometer shall operate normally when subjected to a temperature from -14 °F to +125 °F.

The mounted accelerometer shall have a non-operating temperature range from -30 °F to 215 °F.

Reliability The mounted accelerometer shall have a mean time between failures (MTBF) of greater than 100,000 hours.

Acoustic Sensitivity The mounted accelerometer shall have an acoustic sensitivity of ≤10µg when subjected to a 100 dB SPL source.

Electromagnetic Compatibility The mounted accelerometer shall meet the following MIL-STD-461D and MIL-STD-461C electromagnetic compatibility requirements and limits:

DC Leads (30 Hz – 50kHz); AC Leads (from second harmonic of power frequency, to 50 kHz)

Waterproof The accelerometer and cable assembly, excluding the cable end shall be pressure proof to 5 psi indefinitely.

Humidity The mounted accelerometer shall be designed to operate normally at relative humilities of 0% to 100%.

Shock The mounted accelerometer shall be designed to operate within specification after being subject to a shock of 5000 g peak, 0.5 millisecond half sine from any direction.

Corrosion The accelerometer case material shall be made from a corrosion resistant material.

Frequency Response

MinM 1 3 3 5000 5000 10000 10000 20000 -10 -10 -5 -5 -10 -10 -20 -20 MaxM 1 3 3 5000 5000 10000 10000 20000 10 10 5 5 10 10 20 20 Frequency

Sensitivity [%]

Noise Floor Requirement

New 1 10 100 1000 10000 20000 4 0.8 0.4 0.16 0.16 0.16 Frequency µg/√Hz