classification of Relays

No.		Name			Definition
Electromagnetic relays					Relays that operate “on”、“off” or changeover by the magnetism produced by the control current putted to the coil.
1		Electro- magnetic relay		DC	The control current is direct current. According to the contact load, it can be classified into four kinds of micro power, low power, intermediate power and high power.
2				AC	The control current is alternating current. It can be classified into two kinds of 50Hz and 400Hz according to the frequency of the coil power source.
3				Magnetic latching relay	Using permanent magnet or parts with high remanence to keep the armature at the same position as the coil is electrified when the coil power source is taken away.
4		Solid state relay (SSR)			SSR is a kind of merely solid-state component that can make the whole circuit “on” or “off” as electromagnetic relays do, and the I/O isolation resistance is equivalent to electromagnetic relays.
5		Hybrid relay			The relay is composed of electronic components and electromagnetic relays. Generally, the input part is composed of electronic circuit playing the role of enlargement and rectification; the output part is electromagnetic relay.
6		High frequency relay			The relay is used in AC circuit whose switching frequency exceeds 10kHz.
7		Coaxial relay			The relay is used together with coaxial cable to switch high frequency and RF circuits. But the power consumption is minimum.
8		Vacuum relay			The contact of the relay is sealed in vacuum container. It is used to fleetly switch on, off, or over high voltage, high frequency and RF circuits.
Thermal relay					The relay acts on the effect of heat.
9	Thermal relay		Temperature relay		The relay will act when the ambient temperature rise to a certain value.
10			Electrothermal relay		The relay will act when the heat energy that is from electricity energy in the controlling circuit rise to a certain value.
11	Photoelectrical relay				The relay acts on photoelectric effect.
12	Polarized relay				The relay acts on the effect of the polarized magnetic field and thecontrolling current through the coil. The operating direct depends on the direct of the coil current.
13	Time relay				When input signal is putted on or taken away, output parts won’t turn the controlled circuit on or off until the time is delayed or limited to a specified spot.
14	Reed relay				The relay opens, closes, or changeovers the circuit depending on the action of the reed sealed in the tube. The reed acts as both contact blade and armature.

2.2 Classification on the contact load. Showing in table 2.(Table 2)

Name	Definition
Micro power relay	When the off state voltage of contact is 27VDC, the contact rated load current (resistive load) is 0.1A, 0.2A.
Low power relay	When the off state voltage of contact is 27VDC, the contact rated load current (resistive load) is 0.5A, 1A.
Intermediate power relay	When the off state voltage of contact is 27VDC, the contact rated load current (resistive load) is 2A, 5A.
High power relay	When the off state voltage of contact is 27VDC, the contact rated load current (resistive load) is 10A, 15A, 20A, 25A, 40A, etc.

Note: There is only a kind of DC resistive load showed in the table; other load forms can be calculated according to the product technical conditions.  2.3 Classification on the outline dimension. Showing in table 3. (Table 3)

Name	Definition
Microminiature relay	The dimension of the longest side doesn’t exceed 10mm.
Subminiature relay	The dimension of the longest side exceeds 10mm, but less than 25mm.
Miniature relay	The dimension of the longest side exceeds 25mm, but less than 50mm.

Note: For hermetic or sealed relay, the outline dimension refers to the largest dimension of L, W and H of the relay body itself, not including the dimension of mounting parts, terminals, pushed strip, pushed side, upturned side and sealed welding dot. 2.4 Classification on the protective construction. Showing in table 4.(Table 4)

Name	Definition
Hermetic relay	The contact, coil and other parts are all hermetically sealed in a cover by welding or other means to insulate the relay with ambient media to lessen the leakage.
Sealed relay	The contact, coil and other parts are all sealed (not hermetically) in a cover to protect the relay.
Open relay	There is no protective cover to protect the contact, coil and other parts.