SPD for Power Supply System Series Selection Guide
The installation of SPD at each lightning protection zone, according to the standard of low voltage electrical appearance, make classification of electrical equipment in accordance with the over voltage category, its insulation withstand impulse voltage level can determine the selection of SPD. According to the standard of low voltage electrical appearance, make classification of electrical equipment in accordance with the over voltage category as signal level, loading level, distribution and control level, power supply level. Its insulation withstand impulse voltage level are:1500V,2500V,4000V,6000V. As per to the protected equipment installation position different and the different lightning current of different lightning protection zone, to determine the installation position of SPD for power supply and the break-over capacity.
The installation distance between each level SPD should not more than 10m, the distance between SPD and protected equipment should as short as possible, not more than 10m. If due to limitation of installation position, can't guarantee the installation distance, then need to install decoupling component between each level SPD, make the after class SPD can be protected by the prior class SPD. In the low voltage power supply system, connecting an inductor can achieve the decoupling purpose.
SPD for power supply system specification selection principle
Max. continuous operating voltage: bigger than protected equipment, the system's max. continuous operating voltage.
TT System: Uc≥1.55Uo (Uo is low voltage system to null line voltage)
TN System: Uc≥1.15Uo
IT System: Uc≥1.15Uo(Uo is low voltage system to line voltage)
Voltage Protection Level: less than the insulation withstand impulse voltage of protected equipment
Rated discharge current: determined as per to the lightning situation of the position installed and lightning protection zone.
Normal Working Conditions
-Altitude not exceed 2000m
-Ambient air temperature:
Normal range: -5ºC~+40ºC
Extend range: -40ºC~+80ºC
-Relative Humidity: 30% - 90% under indoor temperature condition
- At the place without obviously shaking and shock vibration
- Non-explosion danger medium, non-corrosion gas and dust ( including conductive dust)
-As per Nominal Discharge Current:
- As per Maximum continuous operating voltage:
- As per to poles
- As per auxiliary functions:
a. With remote signal output ( remote alarm function)
b. Without remote signal output
- The continuous applied voltage on the two terminals of SPD should not more than the maximum continuous operating voltage Uc value;
- The voltage protection level Up of SPD should less than the maximum impulse withstand voltage of the protected equipment;
- As per to the different earthing system and protection mode to select the specification accordingly;
SP1-C (Class II Protection)
SP1-C series SPD is suitable for TT,IT,TN-S,TN-C-S power supply system with AC 50/60Hz,230/400V and below. Its design based on IEC6143-1, GB18802.1 and GB50057 standard requirements. Mainly used for protect the low voltage electrical device to prevent the surge current caused by air discharge (such as lightning) or operating over voltage, used as one kind of voltage limiting device, it equipped with heavy duty zinc oxide varistor.
SP1-C type SPD should installed as near as possible to the upstream line side of the protected equipment (immediately connect to the downstream of incoming line), as earthing device to connecting external conductor (L) or neutral line and user equipment. Installed at transition area of LPZOA/OB and LPZ1 zone or LPZ1 and LPZ2 zone, normally installed at the incoming of low voltage main distribution board.