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tehama-wireless-automated-meter-reading-runtime-mdt-standard-range

MDT

Metering Data Transceiver with Runtime Measurement

Standard, MAX, and LoRaWAN Systems

Product Overview

The Tehama Wireless Runtime MDT records the on-time (in seconds) of distributed-energy equipment. It is offered in three radio technologies—Standard Range, MAX Range, and LoRaWAN. Standard is our first-generation system, which we continue to fully support.

The running count is stored locally and transmitted to the DCAP / Gateway once an hour. Models are available that sense a 24 VAC thermostat-control signal or a dry-contact (relay) input.

Options include an internal ambient-temperature sensor or an external thermistor (dry-contact versions). Thermostat models monitor connection integrity and raise an alert if tampering is detected.

Most Runtime MDTs run on two inexpensive, field-replaceable AA batteries (5-7 yr life). A line-powered version is available for the dry-contact model.

The on-board time base uses a high-accuracy watch crystal and is periodically resynchronized by the DCAP / Gateway over the RF network.

Specifications

Specification	Details
Input Options	• 24 VAC thermostat signal • Dry-contact (relay) input • Internal thermistor sensor • External thermistor sensor
Data Resolution	1-hour reading & transmission interval
Radio	902 – 928 MHz; FCC / IC certified Standard (10 mW): open-field > 1 mile * MAX & LoRaWAN: open-field ≈ 10 miles *
LED	Bi-color LED indicates power and RF-link quality
Operating Environment	-20 ° to 145 °F, ≤ 90 % RH (non-condensing)
Power	• Two AA Alkaline (standard) • Two AA Lithium (sub-freezing) • 2.5 – 3.3 V DC input (LC models)
Typical Battery Life	6 – 8 years @ 50 – 90 °F (reduced at extremes)
Dimensions	3.5″ × 2.1″ × 1.2″
Warranty	Five years (batteries excluded). See warranty page.

Continual product enhancements may cause specifications to change without notice.
*Actual range may vary with installation location and topography.

Models

Standard System	Model #	Description
24 VAC input (battery)	TW-160B-R TW-160B-RI	-R: runtime counter & circuit-fault alert -RI: + internal temperature sensor
Dry-contact input (battery)	TW-160B-RC TW-160B-RCI TW-160B-RCX	-RC: relay runtime counter -RCI: + internal temperature sensor -RCX: + external thermistor
Dry-contact input (line-powered)	TW-160LC-RC(I)	Same as battery models; powered by 2.5 – 3.3 V DC
MAX System	Model #	Description
24 VAC input (battery)	TW-170B-R TW-170B-RI	Same functions as TW-160B equivalents
Dry-contact input (battery)	TW-170B-RC TW-170B-RCI TW-170B-RCX	Same functions as TW-160B equivalents
Dry-contact input (line-powered)	TW-170LC-RC(I)	Line-powered version of TW-170B-RC(I)
LoRaWAN System	Model #	Description
24 VAC input (battery)	TW-180B-R TW-180B-RI	LoRaWAN equivalents of 24 VAC models
Dry-contact input (battery)	TW-180B-RC TW-180B-RCI TW-180B-RCX	LoRaWAN equivalents of dry-contact models
Dry-contact input (line-powered)	TW-180LC-RC(I)	Line-powered LoRaWAN model

Note: Standard, MAX, and LoRaWAN products are NOT cross-compatible; each MDT must be paired with its matching Repeaters, Gateways, and DCAPs.

Refer to AN-119 for additional details.

Usage

Runtime MDTs connect across the 24 VAC terminals of a typical thermostat control signal, usually at the zone valve. They can also be connected at the thermostat across the 24 VAC C (Common) and W (White) terminals; polarity is unimportant. A typical wiring diagram is shown below.

Whenever the thermostat energizes the valve, the MDT increments a seconds counter. You can change units to minutes or hours in Tehama CIT by adjusting the count factor (1⁄60 = 0.0166667 for minutes; 1⁄3600 = 0.00027778 for hours).

The circuit state is sampled every 30 s. Sampling continues even if the MDT is off. If a powered-off MDT detects voltage, it turns on and starts hourly transmissions. Conversely, if a connected MDT loses its circuit, it reports a disconnect and CIT shows “Disconnected” in the Runtime Count field.