Complete Specification of Nickel Cadmium battery Thermal Runaway Isolator

S.No. Content Sheet No

1 Title of the invention 3

2 Field of invention 3

3 Use of invention 3

4 Description 3

5 Concise components 4

6 Physical characteristics of battery Thermal

Runaway Isolator

7 Functional logic table 5

1. Title of the invention

Nickel Cadmium battery Thermal Runaway Isolator

2. Field of invention

It is an electrical engineering design used for aircraft electrical system.

3. Use of invention

This invented Thermal Runaway Isolator finds its applicability in the any type of aircraft
which is having Nickel Cadmium Battery as an emergency electrical power supply.

Thermal Runaway Isolator is designed for charging/discharging, monitoring/protection of Nickel-Cadmium Batteries. It will automatically isolate the battery from charging as well as discharging in the event of thermal run-away and protect the battery without any
personnel intervention.

Thermal run-away is a condition in which the battery temperature raises due to chemical reaction and this raise in temperature accelerate the chemical reaction .This cumulative action will lead to immense rise in battery temperature that may prove to be catastrophic if appropriate action is not taken within stipulated time.

4. Description

This invention relates in general to battery charging/discharging systems, and more particularly to a thermally responsive protection circuit for preventing thermal runaway hazards in nickel cadmium batteries. Nickel cadmium batteries because of their high current capacity, light weight, and ability to operate in a sealed housing, have come into wide use on vehicles such as aircraft where large electrical loads must be handled while keeping weight to a minimum.

The Thermal Runaway Isolator is an Line Replaceable Unit (LRU) working in conjunction with DC Power Distribution Box that distributes power to aircraft loads. The
Thermal Runaway Isolator receives power from Ni-Cd Battery and distributes to DC Power Distribution Box. It monitors the Ni-Cd Battery voltage and temperature and protects Battery in case of Thermal Run-away.

The Thermal Runaway Isolator consists of Direct Current Thermal Protection(DC-TP) Contactor, Thermal protection Relay(TP-Relay), Circuit Breakers(2 nos). Terminal Block & Diode for reverse polarity protection.

The Ni-Cd battery is directly connected to the Thermal Runaway Isolator as shown in the circuit diagram (fig:1). The battery supply is given to the Aircraft DC loads through the un-energized condition of DCTP contactor. At higher temperature, the Battery hot sense signal from the Ni-Cd Battery will energise the thermal relay (TP relay) which in turn energises the DC-TP Contactor and (NC contact will become open) thus the Battery will be isolated from the charging / discharging line. The unit shall provide data on electrical system failure for use by aircraft data acquisition system to evolve necessary warnings to the pilot and maintenance data for ground crew.

5. CONCISE COMPONENTS

The Thermal Runaway Isolator shall contain the following components or functional modules accommodated compactly within the volume and weight given in this specification.

DC Thermal Protection Contactor (DC-TP): DC power contactor 400Amps (It should have normally open contacts for wiring)

It also contains TP-Relay, Circuit Breakers(2-Nos), Terminal Block & Diode for reverse polarity protection

Monitoring Points:

a) Battery Voltage monitoring points

b) Battery connected/ disconnected indication point

c) Temperature sense signal.

d) DC Thermal Protection Contactor monitoring for system health status.

6. PHYSICAL CHARACTERISTICS OF BATTERY Thermal Runaway Isolator

e) Dimension : 160* 100* 100 mm (+ 2 mm)

f) Weight : 1.2 Kg max.

g) Coupling -.Connector MIL-C 38999 SERIES -III

h) Mounting Holes : 140* 76 mm (+0.5 mm), Dia : 5.5 mm

7. Functional logic table

Claims

1. Nickel Cadmium Battery Thermal Runaway Isolator is basically used for isolating the Aircraft internal battery under condition of thermal runaway automatically without any personnel intervention.

2. This invention can be adapted to any aircraft that uses Ni-Cd Battery with thermal
sense outputs.

3. The battery is reconnected automatically to aircraft in case of seizure of thermal runaway condition and subsequent cooling of battery

4. The status of thermal protection contactor and thereby status of battery is made is made available to pilot and ground crew under normal operating condition of aircraft