What is a MicroRTU?

RTU stands for Remote Terminal Unit. MicroRTU is Telemetric's term for their small, inexpensive wireless remote monitoring and control devices. They are a "Micro" RTU because they are much smaller and less expensive than standard RTUs.

What is a DNP-RTM?

RTM stands for Remote Telemetry Module. Telemetric's DNP-RTM communicates using the DNP3 protocol over the cellular data network. This enables communication with Intelligent Electrical Devices (IEDs) on electric utility distribution systems. The DNP-RTM can either be installed as a communications board within the IED enclosure or can be installed externally in its own weatherproof enclosure.

What is a TVM?

The TVM monitors 120 VAC line voltage on single and three-phase power, providing real-time notifications of steady state values, outages and under or over voltage conditions. The present, minimum and maximum measured AC voltage can be reported at preset frequencies or anytime upon request. True RMS measurement of the steady state voltage provides improved accuracies. The present, minimum and maximum readings can be averaged over 3 or 96 seconds. The devices can report type II and III power quality events based on the ITIC (CBEMA) voltage acceptability curve.

What does the TC012 MicroRTU do?

The TC012 monitors and controls fixed or switched capacitor banks. Control is performed through two 30 Amp relays. After an output change, the acknowledgement report includes the AC line voltage, open/close status, and the capacitor bank neutral current.

How can I access my devices?

Data from the Telemetric units can be accessed in two primary ways.

1. An existing SCADA system using SCADA-Xchange
2. Intelligent Web Server

How are data packets and messages transmitted from the Telemetric devices?

The Telemetric devices continuously poll the connected device to preprogrammed parameters. If the device goes out of these limits an alarm is sent. The device then sends a message over the cellular control channel. Data is then transferred to the Telemetric Network Operations Center where information accessible from either an existing SCADA system, or a secure web interface.

What is the control channel?

The advanced mobile telephone service analog cellular telephone system offers a total of 832 channels, half of which are assigned to each of two competing carriers in each market. Each cellular carrier uses 21 of its 416 channels as control channels. Each control channel set consists of a forward control channel and a reverse control channel. The forward control channel is used to send general information from the cellular base station to the cellular telephone. The reverse control channel sends information from the cellular telephone to the base station and the cellular system. The control channels are used to initiate a cellular telephone call.

Cellular control channels are more robust than the voice channels for several reasons. The control channels are digital by design and use majority voting as error detection for all messages sent over the reverse control channel. Each message is transmitted five times via the reverse control channel. If the cellular base station receives the same message for three of the five transmissions, it considers the message to be correct.

The frequency reuse plan for control channels is also different from the reuse plan for voice channels. It is 12 to 1 for control channels and 7 to 1 for voice channels, which reduces interference on the control channels. Most of the control channels operate at the maximum permitted transmit power and slightly reduce the voice channel transmit power. These factors, help make control channel communication a reliable medium.

Can the MicroBurst system get overloaded if too many devices are installed?

There is no practical limit to the number of MicroBurst devices that can be deployed. Actual data from over 200,000 MicroBurst devices deployed in the field shows that very little traffic is generated per device and that most of that traffic is in off-peak hours. One cellular tower can support many more than 10,000 MicroBurst devices without affecting any other users and there are hundreds of cellular towers in a typical city. So in any reasonable size metropolitan or rural area, hundreds of thousands of units can be deployed.

How can I be sure that my data is secure?

The radio used by the Telemetric unit complies with EIA-553 and IS-41, the standards governing secure cellular communications. Each data packet is sent 5 times to ensure integrity. Three of the five must match in order for an acknowledgement to be sent from the cell tower. If an acknowledgement is not received, the Telemetric unit will retry.

All traffic originating from a Telemetric unit is verified against and sent only to the Aeris system. Only authorized units are allowed to transmit data. All traffic is carried across the SS7 network, where every message contains a checksum and has a corresponding acknowledgement message. All data received by Aeris is saved into an Oracle database running on a triply redundant server. When the data packets are sent to the Telemetric web site they must be acknowledged. Unacknowledged data is retransmitted. Telemetric connects to Aeris via a fixed IP address. All connections are routed through a firewall.

On the Telemetric web site, each customer must log in with a unique user ID and password to gain access to their units. Customers only have access to their own units. They can never see anyone else's data.

The Telemetric web server has hard drives that are mirrored to protect against hard drive failure and it is protected by a UPS. The server is housed at an ISP that has multiple T-1 lines. It is protected by a firewall and supports Verisign 128 Bit SSL transaction security.

Do I need to purchase local cellular air time in order to use the Telemetric MicroRTU?

No. Part of the low annual fee that you pay Telemetric covers the communication link used by the Telemetric MicroRTU or RTM. They are treated as a "roaming" cell phone, so they can be installed anywhere that cellular coverage exists.

What does the Telemetric annual service fee include?

Each service plan covers a certain number of reports, alarms and control commands per month, plus ongoing use, maintenance and enhancements to the web site. Excess communication with the MicroRTU or RTM is billed quarterly as overage.

What applications are best suited for using the Control Channel?

The cellular control channel is best suited for sending small packets of data infrequently. Examples of applications include alarms and switching.