Understanding Form A, Form B and Form C Contact arrangements.

Understanding Form A, Form B and Form C Contact arrangements.

“Form A” is a Contact configuration term for relays. It refers to a Single Pole-Single Throw normally open contact. "1 Form A" means there is one Form A contact in the relay, "2 Form A" means there are two "Form A contacts" in the relay, so on and so forth.

Form A Normally Open is the most common configuration for relays. The relay acts as a switch and breaks the circuit. Then a small control voltage or current is applied to close the relay, therefore connecting the circuit.

Bright Toward provides a wide range of contact forms and multi-channel relays, from Optically-coupled MOSFET Relays, Reed Relays, Multi-Channel Reed Relays to our six channel MEMS Switch. To search for Form A normally open relays in our fleet, please click the "MULTIPLE SEARCH" on the upper right of the page and choose the [CONTACT FORM] as you need. Or use the below form to tell us your need, and our professional team will contact you with the suggestion soon.

Bright Toward offers a wide range of Form A Normally Open Relays, from Optically-coupled MOSFET Relays, Reed Relays, Multi-Channel Reed Relays to our six channel MEMS Switch. To search for Form A normally open relays in our fleet, please select your desired "Contact Form" in "multiple search." Or tell us your requirements through below form.

Form B refers to a normally closed Single Pole-Single Throw contact arrangement in a relay. This means that it stays in a closed (off) state without you driving the relay to operate. "1 Form B" means there is one "Form B contact," "2 Form B" means there are two "Form B contacts" in the relay, so on and so forth.

Form C refers to a Single Pole-Double Throw (SPDT) contact, which means that there is one common point connected to one normally open-end and another normally closed contact. "2 Form C" refers to two "Form C contacts," so on and so forth.

• 26 Series: Load Voltage 40V / Load Current 3.5A
• 28 Series: Load Voltage 40V / Load Current 4.5A
• 45 Series: Load Voltage 60V / Load Current 200mA
• 30 Series: Load Voltage 400V / Load Current 120mA
• 38 Series: Load Voltage 600V / Load Current 80mA
• 40 Series: Load Voltage 1500V / Load Current 45mA
• 58 Series: Load Voltage 1800V / Load Current 30mA

• SIP Series (Load Voltage 150V / Load Current 1.75A): 1 Form A (SPST, Normally Open), 1 From B (SPST, Normally Close)
• MSIP Series (Load Voltage 200V / Load Current 1.5A): 1 Form A (SPST, Normally Open), 2 Form A (SPDT, Normally Open)
• DIP Series (Load Voltage 100V/Load Current 1A): 1 Form A (SPST, Normally Open), 2 Form A (Normally Open), 1 Form B (SPST, Normally Close), 1 Form C (SPDT, Normally Open/Normally Close)
• VSIP Series(Load Voltage 230V/Load Current 1A) Switch vertically packaged: 1 Form A (SPST, Normally Open)
• VN Series (Load Voltage 150V/Load Current 1A) Switch vertically packaged with Multi-Channel: 1 Form A (SPST, Normally Open), 2 Form A (SPDT, Normally Open), 4 Form A (SP4T, Normally Open)
• BU Series (DC to 6GHz Load Voltage 210V/Load Current 1A): 1 Form A (SPST, Normally Open), 1 Form C (SPDT, Normally Open/Normally Close)

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