SO-Pd11 beacon

The larger the cross-section of the wires, the lower its resistance and, consequently, the lower the voltage drops. For example, the HDGs 1x2x1.5 mm2 cable has a core resistance of R = 12.1 Ω/km, while the HTKSH 1x2x2.5 mm2 cable has a core resistance of 7.41 Ω/km. In order to calculate the voltage drop, the length of the line should be taken into account and a safety factor related to the length of the wire that may be caught in fire (increase in its resistance) should be assumed.

The resistance of the wires changes as a function of temperature. According to the ISO curve, the temperature of the PH30 cable operating in fire conditions will be 822°C after 30 minutes and its resistance will increase 4.5x! The temperature of the PH90 cable after 90 minutes will be approximately 955°C and its resistance will increase by almost 5.3x! This should be taken into account when designing the installation and appropriate safety factors should be adopted. The resistance of the cable affects voltage drops and, consequently, whether the device will operate in hazardous conditions or not. Voltage drops can be compensated by increasing the cross-section of the conductors.

Degrees of protection provided by enclosures (IP code) is the full name of the PN-EN 60529 standard. It contains a classification of degrees of protection provided by enclosures of electrical devices with a rated voltage up to 72.5 kV.

The code consists of:

• first characteristic digit (against the ingress of foreign solids)
• second characteristic digit (against water ingress)
• additional letter (before access to hazardous parts)
• supplementary letter (supplementary information)

For example, according to EN 54-3, EN 54-23 standards, external fire alarms (type B) must provide IP33C protection. This means that the housing provides protection against:

• access to hazardous parts with a tool (2.5 mm probe)
• foreign bodies with a diameter of 2.5 mm and larger
• water spraying (at any angle up to 60° from the vertical)

The required capacity K [Ah] of the battery(s) can be calculated from the formula:

K=1,25*(I1*t1+I2*t2)

Where:

K – required capacity, in ampere-hours (Ah)

t1 – support time, in hours (h)

t2 – alarm time, in hours (h)

I1 – total current consumed by the fire alarm system in the event of failure of the energy source, in amperes (A)

I2 – total current consumed by the fire alarm system when alarming, in amperes (A)

Yes, it is, though it depends on the number of ordered alarm devices, such devices have a different price. If you are interested, please send an inquiry to us on [email protected].