SENTINEL WMRTU

Look at picture of panel-mounted unit.

The SENTINEL™ Wattmeter RTU accurately measures and computes the power characteristics of 3-phase distribution systems. The unit's analog inputs connect directly to the secondaries of potential (PTs) and current (CTs) transformers, and are rapidly sampled (digitized) to derive true RMS and Watt values. This approach bypasses transducers thereby eliminating their associated calibration and inaccuracy problems.

Six cycles of input sample values are managed until a preset status point (trigger) is activated, or upon demand from a host computer. For example, this event history will provide a high resolution snapshot of the line conditions that caused a feeder breaker to trip. Fourier transforms may be performed on this waveform data to identify line harmonics. The unit also features a set of status inputs and digital outputs for controlling associated devices.

Two ports are available for dedicated communications to a host RTU, a Master Station, and/or dial-up computer. The wattmeter's data can also be accessed on-site with a handheld tester or portable personal computer.

Input/Output: 3AI (120V or 240V PTs) 4AI (5A CTs) 8DI 6DO

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APPLICATIONS

• Remote meter reading
• Improving EMS observability
• Control of feeders and interruptible loads
• Measurement of reactive and/or non-linear loads

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FEATURES

• Reduces support costs by eliminating transducers and their routine calibration
• Waveform memory stores six cycles of sample data for each of the seven analog inputs to provide a high resolution snapshot - on demand and as a post disturbance memory
• Reprogrammable, nonvolatile EEPROM retains configuration data during loss of power
• Industrial quality components and workmanship for long and reliable operation

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SPECIFICATIONS

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Operating environment (electronics)

• Standard -10 to +70°C temperature
• 0 to 95% relative humidity (non-condensing)

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Operating power

• 10-14VDC input power required
• Typical logic current drain 150mA

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Three PT inputs

• Input signal: 0-120VAC (20% overrange)
• Common mode input range: ±440V

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Four CT inputs (neutral current optional)

• Input signal: 0-5A (140% overrange to 12A)
• 0.15W shunt converts 5A to nominal 0.75VAC
• Common mode input range: ±15V

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Analog to digital conversion

• Conversion accuracy: ±0.10% of span, long term
• Conversion resolution: 1 part in 2000
• Integral calibration check (AI point 8)

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Derived measurements

Instantaneous values (for each phase) below presented upon interrogation:

• RMS Voltage
• RMS Current
• VARS
• Watts (sign indicates direction)
• Power Factor

Aggregate values below are presented upon interrogation (and reset upon successful read):

• Accumulated K/MW hours "bought"
• Accumulated K/MW hours "sold"
• Accumulated K/MVAR hours "inductive"
• Accumulated K/MVAR hours "capacitive"
• Three phase K/MW and K/MVAR
• File of input waveform samples

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Eight status inputs (isolated)

• Input signal must sink 5-10mA
  from 12-24VDC source
• Optical coupler input with 5000V isolation

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Six primary control outputs

• Open collectors (sinks 100mA @ 28VDC) formed by fail-safe/redundant circuitry
• Optional interposing relays

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Dual communication ports

• Each port independently configurable for channel (RS232, RS422, RS485), data rate, and protocol (async/sync)

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ADDITIONAL INFORMATION

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Look at picture of panel-mounted unit.

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ORDERING INFORMATION

200084: SENTINEL RTU CARD

200084-001 $1925

Specify communications protocol and/or firmware version when ordering.

PT/CT TERMINATION ASSEMBLY. Barrier strip with precision, low-burden, shunt resistors for conditioning the AC input signal for the logic board.

200125-001 $92

Contact representative for selection of proper "line-post sensors."

OPTIONAL LINE DRIVER CHIPS. These components replace the standard RS-232 line driver I.C. (socketed DIP).

200127-001, RS-485 $24

200127-002, RS-422 $24

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