Nuvation Energy Stack Switchgear User manual

Nuvation Energy Stack Switchgear
Product Manual
Document ID: NE-PM-003 | Revision: 1.0, 2020-09-03
© 2020 Nuvation Energy

Table of Contents
Important Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê1
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê3
1.1. About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê3
2. System Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê4
2.1. Nuvation Energy Stack Switchgear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê7
2.1.1. Mechanical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê7
2.1.2. Internal Hardware Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê14
2.1.3. External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê16
2.2. Nuvation Energy Cell Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê26
2.2.1. System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê26
2.2.2. Mechanical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê26
3. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê30
3.1. Stack Switchgear Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê30
3.1.1. Mechanical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê30
3.1.2. Electrical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê30
3.2. Cell Interface Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê32
3.2.1. Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê32
4. First Power-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê46
5. Using the Stack Switchgear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê47
5.1. Service Disconnect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê47
5.2. Panel Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê48
5.2.1. Power LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê48
5.2.2. Activity LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê48
5.2.3. Fault LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê48
6. Nuvation Energy BMS Software Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê49
6.1. Install the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê49
6.1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê49
6.1.2. Installing the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê49
6.2. Connect to the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê50
6.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê50
6.2.2. Connecting to the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê50
6.3. Upgrade the Nuvation Energy BMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê52
6.3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê52
6.3.2. Enter Service Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê52
6.3.3. Upgrading the Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê52
6.3.4. Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê53
6.4. Generate a Configuration File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê55
6.4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê55
6.4.2. Generating your Configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê55
6.4.3. Edit the Configuration File (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê56
6.5. Import the Configuration File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê57
6.5.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê57

6.5.2. Import the configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê57
6.5.3. Exit Service Lockout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê58
6.5.4. Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê58
6.6. Calibrate the Nuvation Energy BMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê59
6.6.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê59
6.6.2. Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê59
7. Using the Nuvation Energy BMS Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê60
7.1. The Dashboard Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê60
7.1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê60
7.1.2. Warnings and Faults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê60
7.1.3. Stack Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê61
7.1.4. Stack Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê61
7.1.5. State of Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê62
7.1.6. Depth of Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê62
7.1.7. Cell Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê63
7.1.8. Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê64
7.1.9. Nuvation Energy BMS Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê65
7.2. The Details Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê68
7.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê68
7.2.2. Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê68
7.2.3. Battery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê68
7.2.4. Current Limiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê69
7.2.5. Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê69
7.2.6. Cell Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê70
7.2.7. Thermistor Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê71
7.2.8. Open Wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê72
7.3. The Menu Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê74
7.3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê74
7.3.2. Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê74
7.3.3. Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê74
7.3.4. Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê74
7.3.5. Locking and Unlocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê75
7.3.6. Unlock the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê76
7.3.7. About. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê76
7.4. The Status Banner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê77
7.4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê77
7.5. Understanding the Service Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê78
7.5.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê78
7.5.2. Entering Service Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê78
7.5.3. Exiting Service Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê78
7.5.4. Stealing a Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê79
7.5.5. Shutdown Timer for Battery Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê79
7.5.6. Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê79
8. Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê81

9. Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê82
10. Extended Warranty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê83
Appendix A: Stack Switchgear Operating Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê84
External Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê84
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê84
Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê85
Appendix B: Changing the Nuvation Energy BMS Network Configuration . . . . . . . . . . . . . . . . . . . Ê86
BMS Network Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê86
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê86
Modifying the Network Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê86
Appendix C: Nuvation Energy BMS: Best Practices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê88
Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê88
Excess Cable Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê89
System Noise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê90
DC Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê90
Link Bus Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê91

Important Safety Information
The content in this document must be followed in order to ensure safe operation of Nuvation
Energy BMS.
Do NOT energize the system until all connections to the Stack Switchgear unit
and Cell Interface modules have been made.

The wiring of the battery cell voltage and temperature sensing should be
verified before connecting to the Cell Interface modules. The temperature
sensing must be isolated from the cell voltage sensing. Although the Cell
Interface includes protective circuitry to make it more resilient to brief wiring
errors, the same circuitry can result in the battery cells being slowly
discharged. Over time, these wiring errors can cause damage to the Cell
Interface and/or the cells.
Properly insulate or remove any unused wires. Unused wires can couple
excessive system noise into Nuvation Energy BMS which can disrupt
communication and lead to undesirable behaviors.
Insulated handling is required of any connector carrying potentials over 60 V
DC relative to chassis.
Please be aware of high voltages present in your system and follow all
necessary safety precautions.
Continued on next page 
Nuvation Energy Stack Switchgear - Product Manual
Document ID: NE-PM-003 1Rev 1.0, 2020-09-03

(Continued)

Nuvation Energy BMS relies on your system charger to charge the battery
cells; do not leave your charger off while Nuvation Energy BMS is powered
from the stack for prolonged periods of time. Nuvation Energy BMS should be
shut down when the system is in storage to minimize the drain on the cells.
The provided module enclosures are not fire enclosures.

Depending on battery chemistry, there might be a nominal voltage per cell
which adds up in series and is always present. There are many different
battery chemistries with different current capacities, and so high voltage with
high current capacity may be present while connecting Nuvation Energy BMS.
You must use proper electrical safety precautions when handling any part of
Nuvation Energy BMS.

Neither Nuvation Energy or any of its employees shall be liable for any direct,
indirect, incidental, special, exemplary, personal or consequential harm or
damages (including, but not limited to, procurement or substitute goods or
services; loss of use, data, or profits; or business interruption) however caused
and on any theory of liability, whether in contract, strict liability, or tort
(including negligence or otherwise) arising in any way out of the use of this
product.
Nuvation Energy Stack Switchgear - Product Manual
Document ID: NE-PM-003 2Rev 1.0, 2020-09-03

1. Introduction
Thank you for choosing Nuvation Energy BMS.
Nuvation Energy’s Stack Switchgear provides an integrated battery stack management solution that
includes all the hardware and software required to integrate a battery stack into your energy storage
system. Each Stack Switchgear unit contains Nuvation Energy High-Voltage BMS modules and is
designed to be used with other products in the Nuvation Energy BMS family.
You can take advantage of the highly configurable browser-based user interface and custom-tune
Nuvation Energy BMS to your specific target application.
1.1. About this Manual
This Nuvation Energy Stack Switchgear: Product Manual provides mounting and wiring to connect
your Nuvation Energy Stack Switchgear to your system as well as instructions on using the Nuvation
Energy Stack Switchgear.
We thrive on your feedback and what we build is driven by your input. Please submit
support tickets to [e-mail].
Nuvation Energy Stack Switchgear - Product Manual
Document ID: NE-PM-003 3Rev 1.0, 2020-09-03

2. System Overview
The Nuvation Energy Stack Switchgear, shown in Figure 1, is a pre-configured assembly that
incorporates the major functions of Nuvation Energy battery management system into a rack-
mountable unit which includes stack monitoring, electrical disconnects, pre-charging, current sensing,
fuses, and a safety relay for E-Stop. It also includes supporting components like power supplies,
indicator LEDs, and external-facing connectors.
Figure 1. Nuvation Energy Stack Switchgear
There are different amperage configurations available for the base Stack Switchgear unit, listed in
Table 1. Orderable part numbers are listed in Nuvation Energy Stack Switchgear: NUVSSG Datasheet,
available online at https://www.nuvationenergy.com/technical-resources.
Table 1. Nuvation Energy Stack Switchgear variants
Maximum Voltage Rating Maximum Current Rating
1250 V DC
100 A
200 A
300 A
The high-level Stack Switchgear system design is shown in Figure 2. Within a battery stack, the Stack
Switchgear connects to the daisy-chained Nuvation Energy Cell Interface modules. The Cell Interface
modules convert cell voltage and temperature measurements to digital values to be relayed to the
Stack Switchgear, and enable or disable cell balancing as required. Daisy-chaining the Cell Interface
modules facilitates the design of flexible and scalable battery energy storage systems.
Nuvation Energy Stack Switchgear - Product Manual
Document ID: NE-PM-003 4Rev 1.0, 2020-09-03

Figure 2. Stack Switchgear system diagram
In a multi-stack configuration, as shown in Figure 3, each Stack Switchgear unit is responsible for
monitoring the state and safety of one battery stack. All Stack Switchgear units connected to a single
common DC bus in the system may be connected to a single Nuvation Energy Battery Control Panel,
where an Operator Interface provides a unified view and central control of the multi-stack system.
Nuvation Energy Cell Interface and Nuvation Energy Battery Control Panel are sold
separately. Datasheets are available online at https://www.nuvationenergy.com/
technical-resources.
Nuvation Energy Stack Switchgear - Product Manual
Document ID: NE-PM-003 5Rev 1.0, 2020-09-03

Figure 3. Stack Switchgear multi-stack diagram
Nuvation Energy Stack Switchgear - Product Manual
Document ID: NE-PM-003 6Rev 1.0, 2020-09-03

2.1. Nuvation Energy Stack Switchgear
2.1.1. Mechanical Overview
The Stack Switchgear is primarily designed to fit in a standard 19" rack with a 23"-deep cabinet.
However, other mounting possibilities are supported, as the following subsections discuss. Depending
on the desired application, brackets can be ordered with part numbers listed in Nuvation Energy
Stack Switchgear: NUVSSG Datasheet, available online at https://www.nuvationenergy.com/
technical-resources.
The Stack Switchgear is 4U (rack-units) tall. To maintain safe operating temperatures, it is
recommended to leave 1U of space above the unit for airflow. Depending on the environment, active
airflow, and ambient temperature, some cases may require additional space.
The unit weighs 23 kg [50.7 lbs]. Its overall dimensions, as well as mounting-specific ones, are
shown in Section 2.1.1.4. Please refer to https://www.nuvationenergy.com/technical-resources for
access to CAD files.
Rack-Mount, 19"
As mentioned above, this is the most common use-case for mounting the Stack Switchgear, shown in
Figure 4. The mounting brackets allow for adjusting how far the unit protrudes or receeds from the
front of the rack; see Figure 9 for precise dimensions. Also, these brackets are designed to secure the
front of the unit with respect to the front of the rack. As such, the following note is important.
Third-party side-support angle brackets are necessary to uphold the weight of the
unit, in this mounting application. Some examples include Hammond Manufacturing’s
RASA22BK3 or RAAB2436BK products; details are available on their website.
Figure 4. Rack-mount, 19"
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2-Post Rack-Mount, 19" And 23"
Brackets are available for 2-post open-frame racks. Mounting widths of 19" and 23" are supported, as
shown in Figure 5 and Figure 6, respectively.
Note that third-party side-support 2-post-extension brackets are available, though not necessary.
One example is Hammond Manufacturing’s RDAB2U26 product; details are available on their website.
Figure 5. Rack-mount, 2-post, 19"
Figure 6. Rack-mount, 2-post, 23"
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Shelf-Mount
A Stack Switchgear may also be mounted to the surface on which it rests, with the aid of shelf-mount
brackets, as shown in Figure 7
Figure 7. Shelf-mount
Dimensions
This section provides detailed drawings of the Stack Switchgear and its mounting provisions.
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Figure 8. Dimensions, overall
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Figure 9. Dimensions, rack-mount, 19"
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Figure 10. Dimensions, shelf-mount
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Figure 11. Dimensions, 2-post rack-mount, 19"
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Figure 12. Dimensions, 2-post rack-mount, 23"
2.1.2. Internal Hardware Overview
The Nuvation Energy Stack Switchgear internally includes the following major hardware components:
▪Nuvation Energy High-Voltage Stack Controller
▪Nuvation Energy High-Voltage Power Interface
▪Current measuring shunt
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▪Three high-voltage DC contactors
▪Pre-charge circuit
▪Two short-circuit fuses
▪Safety relay (for E-Stop)
The following subsections describe the components in more detail.
Stack Controller and Power Interface
The Stack Switchgear contains a single Nuvation Energy High-Voltage Stack Controller and Nuvation
Energy High-Voltage Power Interface.
The Stack Controller has a central MCU which handles processes and decision-making required by the
battery management system. The Power Interface contains a redundant MCU to handle processes and
decision-making required to control the high-current contactors.
The Stack Controller and Power Interface are UL-recognized components, for use in UL 1973
stationary battery energy storage systems. For more information on the capabilities of the Stack
Controller and Power Interface please refer to the datasheets available online at
https://www.nuvationenergy.com/technical-resources.
Current Measuring Shunt
A precision current shunt in series with the negative side of the stack is used to measure the stack
charging/discharging current. Current measurement is performed by the Power Interface.
DC Contactors
High-voltage contactors are used by the BMS to connect the battery stack to the DC bus. There are
contactors on both the positive and negative sides of the stack. Nuvation Energy BMS opens the
contactors either by request of an external controller or in fault conditions.
A third high-voltage contactor is used in the pre-charge circuit (see Section 2.1.2.4). Contactors with
auxiliary switch feedback are used so the BMS can raise a fault when it detects contactor failure
during opening or closing. Note that the expected lifespan of a contactor is impacted significantly
each time it disconnects under load.
Pre-Charge Circuit
The Stack Switchgear has a pre-charge circuit to ensure safe connection of its battery stack to the DC
bus. The pre-charge circuit temporarily connects the stack to the DC bus through an appropriately
sized power resistor. This resistor allows a smaller current (proportional to the difference in voltage
between the stack and the DC bus) to flow between the stack and the DC bus. After a 5-second pre-
charge timeout, if the measured current is below the pre-set threshold, the BMS bypasses the pre-
charge circuit by connecting the stack directly to the DC bus.
This ensures the battery stack will not connect to the DC bus when an unsafe voltage mismatch is
present. By default, the Stack Switchgear is configured with a 150 Ω, 300 W power resistor, suitable
for a DC bus capacitance of 15 mF at 1000 V and 10 mF at 1250 V. As a custom request, the pre-
charge resistor can be sized specific to the end application.
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Fuses
Inline fuses are used on both the positive and negative connections and are sized according to the
Stack Switchgear variant. See Table 2 for the fuse ratings for each Stack Switchgear variant.
The fuses interrupt a short circuit event; two of them are used to provide redundancy and to permit
use of the Stack Switchgear with an ungrounded battery stack. A microswitch is used on each fuse so
that the BMS can recognize blown fuses and issue a fault alert.
Table 2. Internal fuse ratings
Stack Switchgear Variant Fuse Rating Interrupt Current Rating
1250 V DC, 100 A 200 A 100 kA
1250 V DC, 200 A 315 A 100 kA
1250 V DC, 300 A 450 A 100 kA
Safety Relay (for E-Stop)
The Stack Switchgear has an internal safety relay for monitoring an external E-Stop signal. A safety
relay is used to ensure the relay cannot fail shorted.
This relay meets the requirements of the following standards: EN 954-1, EN 60204-1, VDE 0113-1
and IEC 60204-1. It also has approvals from UL, cUL, CCC and TUV. For more information about the
E-Stop functionality, see Section 2.1.3.4.
2.1.3. External Interfaces
The Nuvation Energy Stack Switchgear provides the following external interfaces:
▪Ethernet
▪Link Bus
▪Internal Power
▪E-Stop
▪Fan Control
▪Battery Stack and DC Bus
▪Grounding Stud
The following subsections describe each interface in more detail.
Ethernet
The Ethernet connector is a standard RJ45 Ethernet jack. Connect external equipment (such as a
network switch or a Nuvation Energy Battery Control Panel) to this connector.
Table 3. Ethernet Connector Pin Assignment
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