TPL-001-5 Compliance:
How to Configure the FCCP for Open-Circuit Detection on
Non-redundant Station DC Supply
This blog serves as a supplement to Multitel’s earlier blog. Multitel proposed a cost-saving solution to electric power utilities looking to comply with the new NERC’s TPL-001-5 regulation without deploying a costly redundant station DC supply system in their substation network.
We recommend reading the TPL-001-5 blog to learn why the FCCP can be used to detect open circuit and to report the condition to a 24/7 network operations center. The intention behind the present blog is to walk power utility personnel through how to provision, install and set up the FCCP for station DC supply systems found in power utility substations. Additional information about NERC’s TPL-001-5 regulation can be found at the end of this blog.
TPL-001-5 Footnote 13c
Power utility substations include a station DC supply that is designed to keep critical services operational when AC power is lost due to an outage. As an example, critical services can be: fault detection equipment, circuit breakers, tripping coils, associated relays, monitoring systems and communication equipment. For various reasons such as budget, reliability and/or floor space, a station DC supply might have been designed without redundancy.
Thus, a single point of failure is considered when a non-redundant station DC supply is associated with protective functions required for normal clearing. The single point of failure must be mitigated by adding an additional charger and an additional battery string.
There is an exception based on Footnote 13c of the TPL-001-5 standard:
c. A single station dc supply associated with protective functions required for Normal Clearing (an exception is a single station dc supply that is both monitored and reported at a Control Center for both low voltage and open circuit).
The location of monitoring is not specified within TPL-001, but it is clear that the “station DC supply” is the component that must be monitored. Station dc supply associated with protective functions includes station batteries, battery chargers, and non- battery-based dc supply.
Monitoring/Reporting for Low Battery Voltage
By standards, a low DC voltage condition is monitored and reported to a control center. For instance, all battery charging systems are equipped with high and low float voltage alarms that operate a dry contact alarm which is then reported to the control center through either the Supervisory Control and Data Acquisition system (SCaDA) or the Remote Telemetry Unit (RTU). Another possibility is to use the SCADA or RTU’s analog input channels to continuously measure the station DC supply voltage, to trigger high or low voltage alarms, and to report directly to the control center.
Monitoring/Reporting for Open Circuit
On the other hand, open-circuit detection is not as trivial. Battery charging systems vary greatly in cost and functionality — some offer an open-circuit fault alarm and some do not. For those that do not offer open-circuit detection, Multitel offers a simple, reliable field-proven sensor that easily installs on any station DC supply. The FCCP (Float Charging Current Probe) is a sensor that installs on the battery cable (charging conductor) and measures precisely the continuous float charging current that maintains the battery in its full State of Charge (SoC). The FCCP sensor detects loss of float charging current, a direct indication of an Open-Circuit condition. To learn more about the FCCP, visit the FCCP product page.
NERC CIP V5
The FCCP does not have any remote connectivity such as Ethernet or serial communication ports. Thus, no need to worry about compliance to North American Electric Reliability Corporation Critical Infrastructure Protection Standards (NERC CIP) which regulates the cyber security programs for the North American electric power sector.
What is the FCCP?
The FCCP is a specialized battery sensor able to precisely measure the small battery float charging current and to withstand repeatable large DC current displacement without impacting its accurate measuring ability. The CP uses a patented measuring technique.
The FCCP is available in two (2) models: one for DC systems and one for UPS systems. Both models share the same technical specifications and features. The difference resides in the FCCP firmware where the UPS model offers a longer sampling rate to reduce the effect of low-frequency noise from the inverter section of UPS systems. For open-circuit detection, Multitel recommends the FCCP DC System. The product has been trusted by power utility companies in North America since the early 2000s.
The FCCP controller can support up to two CTs (Current Transducers). The CT cable length is available in 10’ (3.3m) or 50’ (15.3m). See the table below.
|
Models |
Qty split-core CTs |
CT cable length |
Response time |
|
FCCP DC System |
1 or 2 CTs |
10’ or 50’ |
+/- 10 minutes |
|
FCCP UPS System |
1 or 2 CTs |
10’ or 50’ |
+/- 25 minutes |
Purchasing the FCCP
The FCCP product is based on a patented device design and is produced by Multitel, a Canadian corporation headquartered in Quebec City. The FCCP is currently on the Multitel online store. Do not hesitate to contact the friendly Multitel sales or technical staff who are available during normal business hours (EST) by phone at 418-847-2255 or by email at info@multitel.com.
Setting up the FCCP
A fully-detailed user manual with installation and programming instructions is available from Multitel’s website resources page. The FCCP is essentially composed of two (2) main components: the FCCP controller enclosure and the specialized split-core CT(s). All the wiring is performed at the back of the FCCP controller (see illustration below).
FCCP Back Panel
Powering the FCCP
The FCCP controller power input voltage must be between 18 to 60Vdcw with a power draw of 2.7W to 3.3W for a single CT or dual CT respectively. Typically, the FCCP is powered from a 2 Amps fuse @ 48Vdc when the substation has telecom or communication equipment.
If 48Vdc is not available, an AC/DC power adapter Type 2 that connects to a 120Vac power outlet is available from the Multitel online store. Lastly, a DC/DC converter is also an option, but it is not convenient to install and is more costly of an option than the AC/DC power adapter.
Quick fact related to powering the FCCP:
- All user-selected parameters are stored in non-volatile EEPROM, thus, configured values will never be lost, regardless of how long the FCCP stays without power.
Setting up the FCCP controller
The FCCP controller should be secured on a flat surface such as a cabinet top or on a flat wall surface using the mounting brackets provided with your purchase. An optional 19” or 23” bracket is available to mount the FCCP controller in an open frame rack or server cabinet.
FCCP and CT(s) should not be more than 100’ (33.3m) apart. It is recommended to set up the FCCP controller as close as possible to the monitored battery string.
Setting up the CT(s)
There is no need to open the battery circuit as the split-core designed CT is quick, safe and simple to install. The CT is polarized and must be installed facing the negative post of the battery string, see the pointing arrow sticker on the CT.
The CT is available in two cable lengths, a 10’ (3.3m) or 50’ (15.3m). The cable can be extended in the field with certain precautions following a step-by-step procedure available from support@multitel.com.
The CT cable comes pre-terminated. The cable is usually routed along the battery rack and plugged at the back of the FCCP controller. Do not affix the CT permanently during the installation as you will need to remove it and put it back on for the calibration procedure.
Quick facts about the CT:
- A FCCP controller purchased with a single CT can be equipped with a second CT at anytime;
- The CT aperture diameter is a rectangular shape, 1.5” x 1.75” (3.8 x 4.4 cm);
- The CT aperture can typically accept cable gauges up to 535 MCM or 2×0000 AWG;
- The CT does not need to be installed in the center of the aperture; a smaller battery cable can rest on the side without impacting the accuracy;
- Prevent the CT from being installed 90 degrees with other conductors that could generate magnetic fields; and
- The CT is designed to be used only with the FCCP controller.
Wiring the Dry Contacts (Alarms)
The FCCP has a set of
two (2) dry contacts to indicate an abnormal situation with the float current
exceeds the low or high threshold values.
When ALM_1 operates,
it indicates that the float charging current has exceeded the LOW current
threshold value. However, when the float charging current exceeds the HIGH current
threshold value, both relay ALM_1 and relay ALM_2 will operate. Thus, for open-circuit detection, ALM_1
contact should be used exclusively.
Simply wire the ALM_NO or NC using 22 to 26AWG cable to SCADA/RTU binary input channel and configure accordingly. Use a pair of pliers to crimp the loose pin onto the wire or a special crimping tool from TE Connectivity 58614-1.
Quick facts about the dry contacts:
- ALM_1 and ALM_2 provide NO and NC contacts. However, when the FCCP power is removed, the NO and NC contact for ALM_1 does not match the printing on the label. The reason is simple as the FCCP provides a CPU failure alarm through ALM_1 as well as the LOW current threshold alarm.
- The CPU maintains the ALM_1 energized continuously so if a CPU failure occurs, the relay is de-energized and provides the alarm.
- The relay contact rating is maximum 150Vdc with 0.2A resistive.
- The activation delay values are not user configurable; they have been introduced to remove potential nuisance alarms when the float current is within the range of alarming like during recharge and discharge normal events.
Determine the Current Thresholds
By default, both the HIGH and LOW current thresholds are set to zero (0), disabling the alarms. A HIGH and LOW current threshold must be configured for different purposes. The LOW threshold value will be used to trigger an open-circuit condition and, consequently, operate the ALM_1 contact. However, the HIGH threshold value should be used to detect a pending thermal runaway condition. The configured values are stored in non-volatile memory and will not be lost when a power reset occurs.
Programming the Current Threshold Value
Now that you have
determined the LOW and HIGH current threshold values for your application, power
up the FCCP controller. Once the FCCP is ready, push the MODE button, and each
click of the MODE button will display a different operating parameter. The four (4) LEDs will illuminate in a pattern
to indicate which operating parameter is being configured.
Quick facts about the programming
- The FCCP will default to NORMAL MODE if there is no activity while in the PROGRAM MODE;
- Any value modified will be saved before automatically defaulting back to NORMAL MODE;
- To revert to NORMAL MODE, press the MODE limited-access button until no LEDs are activated;
- When setting a parameter, holding an arrow key for two (2) seconds will trigger the FCCP to begin scrolling values in the respective direction, up or down, at a rate of 10 values per second.
Performing the Calibration Procedure (IMPORTANT)
The FCCP utilizes magnetic fields along with digital filtering techniques to enable a reliable measurement. Since we are dealing with magnetics, the earth’s magnetic field and the electrical apparatus may influence the FCCP measurements. Therefore, the calibration procedure is required once when the product is ready to be put in service. The calibration will only adjust the zero offset. The calibration procedure is simple and can be performed by:
- Turning the power OFF to the FCCP;
- Setting the CT outside the battery cable and placing the CT perpendicularly against the battery cable as close as possible to its intended final location;
- Ensuring the CT opening is thoroughly closed and the locking pin is in position;
- Pressing the UP and DOWN arrow button simultaneously, turning the power ON to the FCCP and keeping the button fully pressed until the LED turns ON and then turns OFF;
- Releasing both buttons — the FCCP is calibrated; and
- Keeping the FCCP powered while you replace and fix the CT in its final location. The CT can then be secured using tie-wraps.
Testing the Open Circuit
Multitel recommends to test the sequence of events with the help of the Control Center. Once the FCCP is completely installed and operational, we recommend to simulate an open-circuit condition through opening the string. This situation is to be determined by the technical expertise of the registered entity. The goal is to test the chain of events and to ensure the FCCP performs the open-circuit detection and the alarm condition is received at the Control Center. It is important to notify users that the FCCP will generate the alarm only if the open-circuit condition remains for a minimum of 30 minutes, due to its sampling rate and to prevent false alarms.
Trending the Float Charging Current Over Time
The FCCP provides two (2) analog output signals: one for sensor A and another for sensor B. Typically, the FCCP comes with a 50mV signal such as shunts do. By connecting the FCCP analog output to a SCADA system, one will be able to trend the value over time and can then perform behavior analytics. Multitel also offers an FCCP with 4-20mA analog output signals. Please contact a Multitel representative for price and availability information.
Quick facts about the programming mode:
- The 50mV analog output is not isolated. If electrical isolation is needed, we recommend using the FCCP model equipped with 4-20mA analog output signal;
- The 4-20mA is a passive meaning the FCCP controller does not provide power to the loop; and
- Note that during discharge and recharge, the analog output signal goes to -60mV and +53mV respectively.
Interpreting the ANALOG outputs
If you have only one CT connected to Sensor A, plug-in the DVM test probes on the FCCP front panel. Set the DVM scale to read millivolts (mV) and use the following table to convert the 0-50mV analog output value displayed on the DVM into your float charging current in milliamps (mA).
Battery Operating Modes | Battery Current | Analog Output Signal | |
50mV | 4-20mA | ||
Battery on “Float” | Current between 0 and 5.3 amperes | 0mA = 0mV 1250mA = 12,5mV 5000mA = 50mV | 0mA = 4mA 1250mA = 8mV 5000mA = 20mA |
Battery on discharge (BOD) | Negative current below 0 ampere. | -60mV | 2mA |
Battery on recharge (BOR) | Positive current beyond 5.3 amperes | +53mV | 20.9mA |
To interpret Sensor B, the DVM test probes must be connected at the back of the FCCP controller where it is labeled “ANALOG” Sensor B. For the FCCP with 4-20mA output signal, set the DVM to read mA and place the leads in series through the 4-20mA loop.
Consider these following FCCP advantages:
- Since the early 2000s, float current measurements have been accepted for determining SoC (State of Charge) of VLA and VRLA batteries (see IEEE-450);
- Contrary to Hall effect transducers, the FCCP digital measurement technique can sustain large discharge and recharge current without any hysteresis effects. It has no remanence, and the measurement does not drift in time;
- The FCCP has smart alarming as it detects discharge and recharge events thus, it will not alarm during these normal battery modes of operation;
- Float current is the parameter of choice when it comes to thermal runaway prevention; and
- The FCCP digital measurement and filtering technique is aimed at providing a pure DC component of the charging current, thus it does not measure ripple current. Also, the FCCP response time can take as much as 20 minutes to stabilize and provide a true measurement.
Disclaimer
Multitel does not provide specific threshold values. Instead, we can provide the following guidance on suggested best practices to configure them according to your monitoring application:
- First determine the nominal (theorical) float charging current value from your product specifications or by contacting your battery vendor/manufacturer.
- Validate that the nominal value is similar to the outputted value from the FCCP (see below to know how to interpret the FCCP analog output value).
- Note that the typical value received by the manufacturer is provided at 25oC/77oF at the nominal float voltage settings. If the battery monitored is operating outside these conditions, this will influence the float charging current level.
- Ohmic Testing of Battery testers and Battery Monitoring Systems do not influence the FCCP measurements.
Monitoring for Thermal Runaway
Thermal runaway is a situation that can lead to cell/jar bulging, acid spills and, ultimately, to catastrophic situations if not detected in time. Although it is more inclined to occur on Vented Regulated Lead Acid (VRLA) batteries, the problem can also be present on Vented Lead Acid (VLA) battery as well. Thus, it can be beneficial to take advantage of the FCCP to protect your operations staff and assets.
TPL-001-5 References
FERC Order No. 754 was addressed in the most recent update of TPL-001-5 standard approved on January 23, 2020 to be fully enforced on July 1, 2023. Out of all changes to TPL-001-5 that were made, two of them are the focus behind this blog:
- Modified Category P5 to include “Single Point of Failure”; and
- Footnote 13c – describes the non-redundant Protection System components that are required to be considered for Category P5.
For more information on the above modifications, follow the link to the NERC TPL-001-5 training available here.
We hope you have enjoyed this article. If some subject matter or questions have not been answered, please do not hesitate to contact a Multitel representative today (info@multitel.com).
